| Adopting agency | BSC | BSC-CG | SFM | HCD | DSA | OSHPD | BSCC | DPH | AGR | DWR | CEC | CA | SL | SLC | |||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 1 | 2 | 1-AC | AC | SS | SS/CC | 1 | 1R | 2 | 3 | 4 | 5 | ||||||||||||
| Adopt entire chapter | X | X | X | X | X | X | X | X | X | X | X | X | |||||||||||
| Adopt entire chapter as amended (amended sections listed below) |
|||||||||||||||||||||||
| Adopt only those sections that are listed below |
|||||||||||||||||||||||
| Chapter / Section | |||||||||||||||||||||||
The Office of the State Fire Marshal’s adoption of this chapter or individual sections is applicable to structures regulated by other state agencies pursuant to Section 1.11.0.
The requirements of this chapter shall
govern the venting of fuel-burning appliances.
Low-heat and
medium-heat gas appliances shall be vented in accordance
with this chapter. Other gas appliances shall be vented in
accordance with NFPA 211 or other applicable standards.
Appliances
fueled by fuels other than gas shall be vented in accordance
with NFPA 211 and the appliance manufacturer's instructions.
Type B and Type B-W gas vents shall comply
with UL 441, Type L gas vents shall comply with UL 641.
Listed vents shall be installed in
accordance with this chapter and the manufacturer's
installation instructions. [NFPA 54:12.2.1]
Appliance vents shall
not discharge into a space enclosed by screens having
openings less than 1/4 of an inch (6.4 mm) mesh.
Except as permitted
in Section 802.2.1 through Section 802.2.8, all appliances
shall be connected to venting systems. [NFPA 54:12.3.1]
The following appliances shall not be required to be
vented:
- Listed ranges.
- Built-in domestic cooking units listed and marked for optional venting.
- Listed hot plates and listed laundry stoves.
- Listed Type 1 clothes dryers exhausted in accordance with Section 504.4.
- A single listed booster-type (automatic instantaneous) water heater, when designed and used solely for the sanitizing rinse requirements of a dishwashing machine, provided that the appliance is installed with the draft hood in place and unaltered, if a draft hood is required, in a commercial kitchen having a mechanical exhaust system; where installed in this manner, the draft hood outlet shall not be less than 36 inches (914 mm) vertically and 6 inches (152 mm) horizontally from any surface other than the appliance.
- Listed refrigerators.
- Counter appliances.
- Room heaters listed for unvented use.
- Direct gas-fired makeup air heaters.
- Other appliances listed for unvented use and not provided with flue collars.
- Specialized appliances of limited input such as laboratory burners or gas lights. [NFPA 54:12.3.2]
Where any or all of the appliances in Section 802.2.1(5) through Section
802.2.1(11) are installed so the aggregate input rating
exceeds 20 Btu/hr/ft3 (207 W/m3) of room or space in
which it is installed, one or more shall be provided with
venting systems or other approved means for conveying
the vent gases to the outdoors so the aggregate input rating
of the remaining unvented appliances does not
exceed 20 Btu/hr/ft3 (207 W/m3). [NFPA 54:12.3.2.1]
Where the calculation includes the volume of an adjacent room or space,
the room or space in which the appliances are installed shall be directly connected to the adjacent room or space
by a doorway, archway, or other opening of comparable
size that cannot be closed. [NFPA 54:12.3.2.2]
Ventilating hoods and
exhaust systems shall be permitted to be used to vent
appliances installed in commercial applications and to
vent industrial appliances, particularly where the process
itself requires fume disposal. [NFPA 54:12.3.3]
The operation of
industrial appliances such that its flue gases are discharged
directly into a large and well-ventilated space
shall be permitted. [NFPA 54:12.3.4]
Listed direct-vent
appliances shall be installed in accordance with the manufacturer's
installation instructions and Section 802.8.2. [NFPA 54:12.3.5]
Appliances incorporating integral venting means shall be
installed in accordance with the manufacturer's installation
instructions, Section 802.8, and Section 802.8.1. [NFPA 54:12.3.6]
Commercial industrial-type
incinerators shall be vented in accordance with NFPA 82.
[NFPA 54:12.3.7]
Venting systems shall
be designed and constructed to convey flue and vent gases to
the outdoors. [NFPA 54:12.1]
A venting
system shall satisfy the draft requirements of the appliance
in accordance with the manufacturer's instructions.
[NFPA 54:12.4.1]
Appliances
required to be vented shall be connected to a venting
system designed and installed in accordance with the
provisions of Section 802.4 through Section 802.15.1.
[NFPA 54:12.4.2]
Mechanical
draft systems shall be listed and installed in accordance
with both the appliance and the mechanical draft system
manufacturer's installation instructions. [NFPA
54:12.4.3.1]
Appliances requiring venting
shall be permitted to be vented by means of mechanical
draft systems of either forced or induced draft
design. [NFPA 54:12.4.3.2]
Forced draft systems and portions
of induced draft systems under positive pressure
during operation shall be designed and installed
so as to prevent leakage of flue or vent gases into a
building. [NFPA 54:12.4.3.3]
Vent connectors
serving appliances vented by natural draft shall not
be connected into any portion of mechanical draft
systems operating under positive pressure. [NFPA
54:12.4.3.4]
Where a mechanical draft
system is employed, provision shall be made to prevent
the flow of gas to the main burners where the
draft system is not performing so as to satisfy the
operating requirements of the appliance for safe performance.
[NFPA 54:12.4.3.5]
The exit terminals of
mechanical draft systems shall be not less than 7 feet
(2134 mm) above finished ground level where
located adjacent to public walkways and shall be
located as specified in Section 802.8 and Section
802.8.1. [NFPA 54:12.4.3.6]
Ventilating hoods and exhaust systems shall be permitted
to be used to vent appliances installed in commercial
applications. [NFPA 54:12.4.4.1]
Where automatically operated appliances, other than
commercial cooking appliances, are vented through
a ventilating hood or exhaust system equipped with
a damper or with a power means of exhaust, provisions
shall be made to allow the flow of gas to the
main burners where the damper is open to a position
to properly vent the appliance and where the power
means of exhaust is in operation. [NFPA
54:12.4.4.2]
Venting systems shall not extend into or pass
through a fabricated air duct or furnace plenum. [NFPA 54:12.4.5.1]
Where a venting system passes through
an above-ceiling air space or other nonducted portion of
an air-handling system, it shall conform to one of the following
requirements:
- The venting system shall be a listed special gas vent, other system serving a Category III or Category IV appliance, or other positive pressure vent, with joints sealed in accordance with the appliance or vent manufacturer's instructions.
- The vent system shall be installed such that no fittings or joints between sections are installed in the above-ceiling space.
- The venting system shall be installed in a conduit or enclosure with joints between the interior of the enclosure and the ceiling space sealed. [NFPA 54:12.4.5.2]
The type of
venting system to be used shall be in accordance with Table
802.4. [NFPA 54:12.5.1]
| APPLIANCES | TYPE OF VENTING SYSTEM | LOCATION OF REQUIREMENTS |
| Listed Category I appliances | Type B gas vent | Section 802.6 |
| Listed appliances equipped with draft hood | Chimney | Section 802.5 |
| Appliances listed for use with Type B gas vent | Single-wall metal pipe Listed chimney lining system for gas venting Special gas vent listed for these appliances |
Section 802.7 Section 802.5.3 Section 802.4.3 |
| Listed vented wall furnaces | Type B-W gas vent | Section 802.6, Section 907.0 |
| Category II appliances Category Ill appliances Category IV appliances |
As specified or furnished by manufacturers of listed appliances |
Section 802.4.1 and Section 802.4.3 |
| Incinerators | Single-wall metal pipe | NFPA 82 |
| Appliances that can be converted to use of solid fuel Unlisted combination gas- and oil-burning appliances Combination gas- and solid-fuel-burning appliances Appliances listed for use with chimneys only Unlisted appliances |
Chimney | Section 802.5 |
| Listed combination gas- and oil-burning appliances | Type L vent Chimney |
Section 802.6 Section 802.5 |
| Decorative appliances in vented fireplace | Chimney | Section 911.2 |
| Gas-fired toilets | Single-wall metal pipe | Section 802.7, Section 929.3 |
| Direct-vent appliances | - | Section 802.2.6 |
| Appliances with integral vents | - | Section 802.2.7 |
Where plastic piping is used to
vent an appliance, the appliance shall be listed for use
with such venting materials and the appliance manufacturer's
installation instructions shall identify the specific
plastic piping material. [NFPA 54:12.5.2]
Plastic pipe and fittings
used to vent appliances shall be installed in accordance
with the appliance manufacturer's installation instructions.
Where primer is required, it shall be of a contrasting
color. [NFPA 54:12.5.3]
Special gas vents shall be
listed and installed in accordance with the special gas
vent manufacturer's installation instructions. [NFPA
54:12.5.4]
Chimneys shall be installed in accordance with Section
802.5.1 through Section 802.5.3.
Factory-built
chimneys shall be installed in accordance with the manufacturer's
installation instructions. Factory-built chimneys
used to vent appliances that operate at positive vent
pressure shall be listed for such application. [NFPA
54:12.6.1.1]
Decorative
shrouds addressed in Section 802.5.4.3 shall be
listed or labeled in accordance with UL 103 for factory-built residential chimneys, UL 127 for factory-built
fireplaces, or UL 1482 for solid-fuel room
heaters.
Factory-built
chimneys shall comply with the requirements of UL
103 or of UL 959. Factory-built chimneys for use with
wood-burning appliances shall comply with the Type
HT requirements of UL 103. [NFPA 211:6.1.3.1, 6.1.3.2]
Metal chimneys shall be
built and installed in accordance with NFPA 211. [NFPA
54:12.6.1.2]
Masonry chimneys
shall be built and installed in accordance with NFPA 211
and lined with approved clay flue lining, a listed chimney
lining system, or other approved material that resists corrosion, erosion, softening, or cracking from vent gases
at temperatures not exceeding 1800°F (982°C).
Exception: Masonry chimney flues lined with a chimney
lining system specifically listed for use with listed
appliances with draft hoods, Category I appliances, and
other appliances listed for use with Type B vents shall be
permitted. The liner shall be installed in accordance with
the liner manufacturer's installation instructions. A permanent
identifying label shall be attached at the point
where the connection is to be made to the liner. The label shall read: "This chimney liner is for appliances that burn
gas only. Do not connect to solid-or liquid-fuel-burning
appliances or incinerators." [NFPA 54:12.6.1.3]
A chimney for a residential-type
or low-heat appliance shall extend not less than 3 feet
(914 mm) above the highest point where it passes
through a roof of a building and not less than 2 feet (610 mm) higher than a portion of a building within a horizontal
distance of 10 feet (3048 mm). (See Figure
802.5.4) [NFPA 54:12.6.2.1]
FIGURE 802.5.4
TYPICAL TERMINATION LOCATIONS FOR CHIMNEYS AND SINGLE-WALL METAL PIPES SERVING RESIDENTIAL-TYPE AND LOW-HEAT APPLIANCE [NFPA 54: FIGURE A.12.6.2.1]
- Termination 10 ft.(3.0 m) or Less from Ridge, Wall, or Parapet
- Termination More Than 10 ft.(3.0 m) from Ridge, Wall, or Parapet
TYPICAL TERMINATION LOCATIONS FOR CHIMNEYS AND SINGLE-WALL METAL PIPES SERVING RESIDENTIAL-TYPE AND LOW-HEAT APPLIANCE [NFPA 54: FIGURE A.12.6.2.1]
A
chimney for medium-heat appliance shall extend at
least less than 10 feet (3048 mm) higher than any portion of any building within 25 feet (7620 mm).
[NFPA 54:12.6.2.2]
A chimney shall
extend not less than 5 feet (1524 mm) above the
highest connected appliance draft hood outlet or flue
collar. [NFPA 54:12.6.2.3]
Decorative
shrouds shall not be installed at the termination of
factory-built chimneys except where such shrouds
are listed and labeled for use with the specific factory-built chimney system and are installed in accordance
with the manufacturer's installation
instructions. [NFPA 54:12.6.2.4]
The effective area of a
chimney venting system serving listed appliances with
draft hoods, Category I appliances, and other appliances
listed for use with Type B vents shall be in accordance
with one of the following methods:
- Those listed in Section 803.0.
- For sizing an individual chimney venting system for a single appliance with a draft hood, the effective areas of the vent connector and chimney flue shall be not less than the area of the appliance flue collar or draft hood outlet or greater than seven times the draft hood outlet area.
- For sizing a chimney venting system connected to two appliances with draft hoods, the effective area of the chimney flue shall be not less than the area of the larger draft hood outlet plus 50 percent of the area of the smaller draft hood outlet or greater than seven times the smaller draft hood outlet area.
- Chimney venting systems using mechanical draft shall be sized in accordance with approved engineering methods.
- Other approved engineering methods. [NFPA 54:12.6.3.1]
This
inspection shall be made after chimneys, vents, or parts
thereof, authorized by the permit, have been installed and
before such vent or part thereof has been covered or concealed.
Before replacing
an existing appliance or connecting a vent connector to
a chimney, the chimney passageway shall be examined to
ascertain that it is clear and free of obstructions and shall
be cleaned where previously used for venting solid- or
liquid-fuel-burning appliances or fireplaces. [NFPA
54:12.6.4.1]
Chimneys shall be lined in
accordance with NFPA 211.
Exception: Existing chimneys shall be permitted to
have their use continued when an appliance is
replaced by an appliance of similar type, input rating,
and efficiency, where the chimney complies with Section 802.5.7 through Section 802.5.7.3 and
the sizing of the chimney is in accordance with Section
802.5.5. [NFPA 54:12.6.4.2]
Cleanouts shall be examined
to determine that they will remain tightly closed
where not in use. [NFPA 54:12.6.4.3]
Where inspection
reveals that an existing chimney is not safe for the
intended application, it shall be repaired, rebuilt,
lined, relined, or replaced with a vent or chimney in
accordance with NFPA 211, and shall be approved
for the appliances to be attached. [NFPA
54:12.6.4.4]
An appliance shall not be connected to a
chimney flue serving a separate appliance designed to
burn solid fuel. [NFPA 54:12.6.5.1]
Where one chimney serves gas appliances
and liquid fuel-burning appliances, the appliances
shall be connected through separate openings
or shall be connected through a single opening
where joined by a fitting located as close as practical
to the chimney. Where two or more openings are
provided into one chimney flue, they shall be at different
levels. Where the gas appliance is automatically
controlled, it shall be equipped with a safety
shutoff device. [NFPA 54:12.6.5.2]
A listed combination gas-and
solid-fuel-burning
appliance connected to a single chimney
flue shall be equipped with a manual reset device to
shut off gas to the main burner in the event of sustained
backdraft or flue gas spillage. The chimney
flue shall be sized to properly vent the appliance.
[NFPA 54:12.6.5.3]
A single chimney flue serving a listed
combination gas- and oil-burning appliance shall be
sized to properly vent the appliance. [NFPA 54:12.6.5.4]
All portions of chimneys
shall be supported for the design and weight of the
materials employed. Listed factory-built chimneys shall
be supported and spaced in accordance with the manufacturer's
installation instructions.
[NFPA 54:12.6.6]
Where a chimney that formerly
carried flue products from liquid or solid fuel-burning
appliances is used with an appliance using fuel gas, an
accessible cleanout shall be provided. The cleanout shall
have a tight-fitting cover and be installed so its upper edge
is not less than 6 inches (152 mm) below the lower edge
of the lowest chimney inlet opening. [NFPA 54:12.6.7]
The remaining space surrounding a chimney liner, gas vent,
special gas vent, or plastic piping installed within a
masonry chimney shall not be used to vent another appliance.
Exception: The insertion of another liner or vent within
the chimney as provided in this code and the liner or vent
manufacturer's instructions.
[NFPA 54:12.6.8.1]
The remaining space
surrounding a chimney liner, gas vent, special gas
vent, or plastic piping installed within a masonry,
metal or factory-built chimney flue shall not be used
to supply combustion air.
Exception: Direct-vent appliances designed for
installation in a solid-fuel-burning fireplace where
installed in accordance with the manufacturer's
installation instructions.
[NFPA 54:12.6.8.2]
The installation of gas vents shall meet
the following requirements:
- Gas vents shall be installed in accordance with the manufacturer's installation instructions.
- A Type B-W gas vent shall have a listed capacity not less than that of the listed vented wall furnace to which it is connected.
- Gas vents installed within masonry chimneys shall be installed in accordance with the manufacturer's installation instructions. Gas vents installed within masonry chimneys shall be identified with a permanent label installed at the point where the vent enters the chimney. The label shall contain the following language: "This gas vent is for appliances that burn gas. Do not connect to solid or liquid fuel-burning appliances or incinerators."
- Screws, rivets, and other fasteners shall not penetrate the inner wall of double-wall gas vents, except at the transition from the appliance draft hood outlet, flue collar, or single-wall metal connector to a double-wall vent. [NFPA 54:12.7.1]
A gas vent shall
terminate in accordance with one of the following:
FIGURE 802.6.1
GAS VENT TERMINATION LOCATIONS FOR LISTED CAPS 12 INCHES OR LESS IN SIZE NOT LESS THAN 8 FEET FROM A VERTICAL WALL [NFPA 54: FIGURE 12.7.2]
For SI units: 1 inch = 25.4 mm, 1 foot = 304.8 mm
- Gas vents that are 12 inches (300 mm) or less in size and located not less than 8 feet (2438 mm) from a vertical wall or similar obstruction shall terminate above the roof in accordance with Figure 802.6.1 and Table 802.6.1.
- Gas vents that are over 12 inches (300 mm) in size or are located less than 8 feet (2438 mm) from a vertical wall or similar obstruction shall terminate not less than 2 feet (610 mm) above the highest point where they pass through the roof and not less than 2 feet (610 mm) above a portion of a building within 10 feet (3048 mm) horizontally.
- Industrial appliances as provided in Section 802.2.5.
- Direct-vent systems as provided in Section 802.2.6.
- Appliance with integral vents as provided in Section 802.2.7.
- Mechanical draft systems as provided in Section 802.3.3 through Section 802.3.3.5.
- Ventilating hoods and exhaust systems as provided in Section 802.3.4 and Section 802.3.4.1. [NFPA 54:12.7.2(1)]
GAS VENT TERMINATION LOCATIONS FOR LISTED CAPS 12 INCHES OR LESS IN SIZE NOT LESS THAN 8 FEET FROM A VERTICAL WALL [NFPA 54: FIGURE 12.7.2]
| ROOF PITCH | H (minimum) (feet) |
| Flat to 6/12 | 1.0 |
| Over 6/12 to 7/12 | 1.25 |
| Over 7/12 to 8/12 | 1.5 |
| Over 8/12 to 9/12 | 2.0 |
| Over 9/12 to 10/12 | 2.5 |
| Over 10/12 to 11/12 | 3.25 |
| Over 11/12 to 12/12 | 4.0 |
| Over 12/12 to 14/12 | 5.0 |
| Over 14/12 to 16/12 | 6.0 |
| Over 16/12 to 18/12 | 7.0 |
| Over 18/12 to 20/12 | 7.5 |
| Over 20/12 to 21/12 | 8.0 |
A Type B or a
Type L gas vent shall terminate not less than 5 feet
(1524 mm) in vertical height above the highest connected
appliance draft hood or flue collar. [NFPA 54:12.7.2(2)]
A Type B-W gas vent
shall terminate not less than 12 feet (3658 mm) in
vertical height above the bottom of the wall furnace.
[NFPA 54:12.7.2(3)]
A gas vent
extending through an exterior wall shall not terminate
adjacent to the wall or below eaves or parapets, except
as provided in Section 802.2.6 and Section 802.3.3
through Section 802.3.3.5. [NFPA 54:12.7.2(4)]
Decorative
shrouds shall not be installed at the termination of
gas vents except where such shrouds are listed for
use with the specific gas venting system and are
installed in accordance with the manufacturer's
installation instructions. [NFPA 54:12.7.2(5)]
A gas vent shall
extend through the roof flashing, roof jack, or roof
thimble and terminate with a listed cap or listed roof
assembly. [NFPA 54:12.7.2(6)]
A gas vent shall terminate not less than 3 feet (914 mm) above a forced
air inlet located within 10 feet (3048 mm). [NFPA
54:12.7.2(7)]
Where a vent passes
through an insulated assembly, an approved metal
shield shall be installed between the vent and insulation.
The shield shall extend not less than 2 inches
(51 mm) above the insulation and be secured to the
structure in accordance with the manufacturer's
installation instructions.
Venting systems shall be
sized and constructed in accordance with Section 803.0
or other approved engineering methods and the gas vent
and the appliance manufacturer's instructions. [NFPA
54:12.7.3]
The sizing of
natural draft venting systems serving one or more
listed appliances equipped with a draft hood or
appliances listed for use with a Type B gas vent,
installed in a single story of a building, shall be in
accordance with one of the following:
- The provisions of Section 803.0.
- Vents serving fan-assisted combustion system appliances, or combinations of fan-assisted combustion system and draft hood-equipped appliances shall be sized in accordance with Section 803.0 or other approved engineering methods.
- For sizing an individual gas vent for a single, draft hood-equipped appliance, the effective area of the vent connector and the gas vent shall be not less than the area of the appliance draft hood outlet or exceeding seven times the draft hood outlet area.
- For sizing a gas vent connected to two appliances, with draft hoods, the effective area of the vent shall be not less than the area of the larger draft hood outlet plus 50 percent of the area of the smaller draft hood outlet or exceeding seven times the smaller draft hood outlet area.
- Approved engineering practices. [NFPA 54:12.7.3.1]
Type B and Type L vents
sized in accordance with Section 802.6.2.1(3) or
Section 802.6.2.1(4) shall extend in a generally vertical
direction with offsets not exceeding 45 degrees
except that a vent system having not more than one 60 degree offset shall be permitted. Any angle
greater than 45 degrees from the vertical is considered
horizontal. The total horizontal distance of a
vent plus the horizontal vent connector serving draft
hood-equipped appliances shall not be greater than
75 percent of the vertical height of the vent. [NFPA
54:12.7.3.2]
The sizing of gas vents for
Category II, Category III, and Category IV appliances
shall be in accordance with the appliance manufacturer's
instructions. The sizing of plastic pipe
specified by the appliance manufacturer as a venting
material for Category II, Category III, and Category
IV appliances shall be in accordance with the
appliance manufacturers' instructions. [NFPA 54:12.7.3.3]
Chimney venting systems using
mechanical draft shall be sized in accordance with
approved engineering methods. [NFPA 54:12.7.3.4]
A common vent shall be permitted in
multistory installations to vent Category I appliances
located on more than one floor level, provided the venting
system is designed and installed in accordance with
approved engineering methods.
For the purpose of this section, crawl spaces, basements, and attics shall be considered as floor levels. [NFPA 54:12.7.4.1]
For the purpose of this section, crawl spaces, basements, and attics shall be considered as floor levels. [NFPA 54:12.7.4.1]
Appliances connected
to the common vent shall be located in rooms
separated from an occupiable space. Each of these
rooms shall have provisions for an adequate supply
of combustion, ventilation, and dilution air that is
not supplied from an occupiable space. (See Figure
802.6.3.1) [NFPA 54:12.7.4.2]
FIGURE 802.6.3.1
PLAN VIEW OF PRACTICAL SEPARATION METHOD FOR MULTISTORY GAS VENTING [NFPA 54: FIGURE A.12.7.4.2]
PLAN VIEW OF PRACTICAL SEPARATION METHOD FOR MULTISTORY GAS VENTING [NFPA 54: FIGURE A.12.7.4.2]
The size of the connectors and common segments of multistory
venting systems for appliances listed for use
with a Type B double-wall gas vent shall be in accordance
with Table 803.2(1), provided all of the following apply:
FIGURE 802.6.3.2
USE OF MANIFOLDED COMMON VENT CONNECTOR
[NFPA 54:FIGURE F.1(k)]
- The available total height (H) for each segment of a multistory venting system is the vertical distance between the level of the highest draft hood outlet or flue collar on that floor and the centerline of the next highest interconnection tee.
- The size of the connector for a segment is determined from the appliance's gas input rate and available connector rise, and shall not be smaller than the draft hood outlet or flue collar size.
- The size of the common vertical vent segment, and of the interconnection tee at the base of that segment, is based on the total appliance's gas input rate entering that segment and its available total height. [NFPA 54:12.7.4.3]
USE OF MANIFOLDED COMMON VENT CONNECTOR
[NFPA 54:FIGURE F.1(k)]
Gas vents shall be
supported and spaced in accordance with the manufacturer's
installation instructions. [NFPA 54:12.7.5]
In those localities where solid and
liquid fuels are used extensively, gas vents shall be permanently
identified by a label attached to the wall or ceiling
at a point where the vent connector enters the gas
vent. The label shall read: "This gas vent is for appliances
that burn gas. Do not connect to solid or liquid
fuel-burning appliances or incinerators. "The Authority
Having Jurisdiction shall determine whether its area constitutes
such a locality. [NFPA 54:12.7.6]
Single-wall metal pipe
shall be constructed of galvanized sheet steel not less than
0.0304 of an inch (0.7722 mm) thick or of other approved,
noncombustible, corrosion-resistant material.
[NFPA 54:12.8.1]
Uninsulated single-wall metal
pipe shall not be used outdoors for venting appliances in
regions where the 99 percent winter design temperature
is below 32°F (0°C). [NFPA 54:12.8.2]
The termination of single-wall
metal pipe shall meet the following requirements:
- Single-wall metal pipe shall terminate at least 5 feet (1524 mm) in vertical height above the highest connected appliance draft hood outlet or flue collar.
- Single-wall metal pipe shall extend at least 2 feet (610 mm) above the highest point where it passes through a roof of a building and at least 2 feet (610 mm) higher than any portion of a building within a horizontal distance of 10 feet (3048 mm). (See Figure 802.5.4)
- An approved cap or roof assembly shall be attached to the terminus of a single-wall metal pipe. [NFPA 54:12.8.3]
Single-wall metal pipe shall not be used
as a vent in dwellings and residential occupancies.
[NFPA 54:12.8.4.1]
Single-wall metal pipe
shall be used for runs directly from the space in
which the appliance is located through the roof or
exterior wall to the outer air. A pipe passing through
a roof shall extend without interruption through the
roof flashing, roof jacket, or roof thimble. [NFPA
54:12.8.4.2]
Single-wall
metal pipe shall not originate in an unoccupied
attic or concealed space and shall not pass through
an attic, inside wall, concealed space, or floor.
[NFPA 54:12.8.4.3]
Minimum clearances from single-wall metal pipe to combustible material shall
be in accordance with Table 802.7.3.3. Reduced
clearances from single-wall metal pipe to combustible
material shall be as specified for vent connectors
in Table 303.10.1. [NFPA 54:12.8.4.4]
For SI units: 1 inch= 25.4 mm
* These clearances shall apply unless the installation instructions of a listed appliance or connector specify different clearances, in which case the listed clearances shall apply.
| MINIMUM DISTANCE FROM COMBUSTIBLE MATERIAL (inches) | ||||
| APPLIANCE | LISTED TYPE B GAS VENT MATERIAL |
LISTED TYPE L VENT MATERIAL |
SINGLE-WALL METAL PIPE |
FACTORY-BUILT CHIMNEY SECTIONS |
| Listed appliance with draft hoods and appliance listed for use with Type B gas vents |
As listed | As listed | 6 | As listed |
| Residential boilers and furnaces with listed gas conversion burner and with draft hood |
6 | 6 | 9 | As listed |
| Residential appliances listed for use with Type L vents | Not permitted | As listed | 9 | As listed |
| Listed gas-fired toilets | Not permitted | As listed | As listed | As listed |
| Unlisted residential appliances with draft hood | Not permitted | 6 | 9 | As listed |
| Residential and low-heat appliance other than those above | Not permitted | 9 | 18 | As listed |
| Medium-heat appliance | Not permitted | Not permitted | 36 | As listed |
* These clearances shall apply unless the installation instructions of a listed appliance or connector specify different clearances, in which case the listed clearances shall apply.
Single-wall metal pipe shall not pass through a combustible
exterior wall unless guarded at the point of passage
by a ventilated metal thimble not smaller than the
following:
- For listed appliances with draft hoods and appliances listed for use with Type B gas vents, the thimble shall be a minimum of 4 inches (102 mm) larger in diameter than the metal pipe. Where there is a run of not less than 6 feet (1829 mm) of metal pipe in the opening between the draft hood outlet and the thimble, the thimble shall be a minimum of 2 inches (51 mm) larger in diameter than the metal pipe.
- For unlisted appliances having draft hoods, the thimble shall be a minimum of 6 inches (152 mm) larger in diameter than the metal pipe.
- For residential and low-heat appliances, the thimble shall be a minimum of 12 inches (305 mm) larger in diameter than the metal pipe.
Exception: In lieu of thimble protection, combustible
material in the wall shall be removed a sufficient distance
from the metal pipe to provide the specified
clearance from such metal pipe to combustible material.
Any material used to close up such opening shall
be noncombustible. [NFPA 54:12.8.4.6]
Where a single-wall metal pipe passes through a roof constructed of combustible
material, a noncombustible, nonventilating
thimble shall be used at the point of passage. The
thimble shall extend not less than 18 inches (457
mm) above and 6 inches (152 mm) below the roof with the annular space open at the bottom and closed
at the top. The thimble shall be sized in accordance
with Section 802.7.3.4. [NFPA 54:12.8.4.5]
Single-wall
metal piping shall comply with Section 802.7.4.1 through
Section 802.7.4.3. [NFPA 54:12.8.5]
A venting
system of a single-wall metal pipe shall be sized in
accordance with one of the following methods and
the appliance manufacturer's instructions:
- For a draft hood-equipped appliance, in accordance with Section 803.0.
- For a venting system for a single appliance with a draft hood, the areas of the connector and the pipe each shall not be less than the area of the appliance flue collar or draft hood outlet, whichever is smaller. The vent area shall not exceed seven times the draft hood outlet area.
- Other approved engineering methods. [NFPA 54:12.8.5(1)]
Where a single-wall metal pipe is used and has a shape other
than round, it shall have an effective area equal to
the effective area of the round pipe for which it is
substituted, and the internal dimension of the pipe
shall be not less than 2 inches (51 mm). [NFPA 54:12.8.5(2)]
The vent cap or a
roof assembly shall have a venting capacity not less
than that of the pipe to which it is attached. [NFPA
54:12.8.5(3)]
Portions
of single-wall metal pipe shall be supported for the
design and weight of the material employed. [NFPA
54:12.8.6]
Single-wall metal pipe shall comply
with the marking provisions of Section 802.6.5. [NFPA
54:12.8.7]
A mechanical
draft venting system shall terminate at least 3 feet (914
mm) above any forced air inlet located within 10 feet (3048
mm). (See Figure 802.8)
FIGURE 802.8
EXIT TERMINALS OF MECHANICAL DRAFT AND DIRECT-VENT VENTING SYSTEMS
[NFPA 54:FIGURE A.12.9]
Exceptions:
- This provision shall not apply to the combustion-air intake of a direct-vent appliance.
- This provision shall not apply to the separation of the integral outdoor-air inlet and flue gas discharge of listed outdoor appliances. [NFPA 54:12.9.1]
EXIT TERMINALS OF MECHANICAL DRAFT AND DIRECT-VENT VENTING SYSTEMS
[NFPA 54:FIGURE A.12.9]
A
mechanical draft venting system of other than direct-vent
type shall terminate not less than 4 feet (1219 mm)
below, 4 feet (1219 mm) horizontally from, or 1 foot (305
mm) above a door, operable window, or gravity air inlet
into a building. The bottom of the vent terminal shall be
located not less than 12 inches (305 mm) above finished
ground level. [NFPA 54:12.9.2]
The vent terminal of a
direct-vent appliance with an input of 10000 Btu/h (3 kW)
or less shall be located at least 6 inches (152 mm) from
any air opening into a building, an appliance with an input over 10000 Btu/h (3 kW) but not over 50000 Btu/h (14.7
kW) shall be installed with a 9 inch (229 mm) vent termination
clearance, and an appliance with an input exceeding
50000 Btu/h (14.7 kW) shall have at least a 12 inch
(305 mm) vent termination clearance. The bottom of the
vent terminal and the air intake shall be located at least 12
inches (305 mm) above finished ground level. [NFPA
54:12.9.3]
Through-the-wall vents for
Category II and Category IV appliances and noncategorized
condensing appliances shall not terminate over
public walkways or over an area where condensate or
vapor could create a nuisance or hazard or could be detrimental to the operation of regulators, relief valves, or
other equipment. Where local experience indicates that
condensate is a problem with Category I and Category
III appliances, this provision shall also apply.
Drains for condensate shall be installed in accordance with the appliance and the vent manufacturer's installation instructions. [NFPA 54:12.9.4]
Drains for condensate shall be installed in accordance with the appliance and the vent manufacturer's installation instructions. [NFPA 54:12.9.4]
Where vents, including
those for direct-vent appliances or combustion air intake
pipes, penetrate outside walls of buildings, the annular
spaces around such penetrations shall be permanently
sealed using approved materials to prevent entry of combustion
products into the building.
[NFPA 54:12.9.5]
Vent systems for Category IV appliances that terminate through an outside wall of a building and discharge flue gases perpendicular to the
adjacent wall shall be located not less than 10 feet (3048
mm) horizontally from an operable opening in an adjacent
building.
Exception: This shall not apply to vent terminals that are
2 feet (610 mm) or more above or 25 feet (7620 mm) or
more below operable openings.
[NFPA 54:12.9.6]
Provision shall be made to
collect and dispose of condensate from venting systems serving
Category II and Category IV appliances and noncategorized
condensing appliances in accordance with Section
802.8.3. [NFPA 54:12.10.1]
Where local experience
indicates that condensation is a problem, provision shall be
made to drain off and dispose of condensate from venting
systems serving Category I and Category III appliances in
accordance with Section 802.8.3.
[NFPA 54:12.10.2]
A vent connector shall be used to connect an appliance to a
gas vent, chimney, or single-wall metal pipe, except where
the gas vent, chimney, or single-wall metal pipe is directly
connected to the appliance.
[NFPA 54:12.11.1]
A vent connector shall be made of
noncombustible, corrosion resistant material capable of
withstanding the vent gas temperature produced by the
appliance and of a thickness to withstand physical damage.
[NFPA 54:12.11.2.1]
Where the vent
connector used for an appliance having a draft hood
or a Category I appliance is located in or passes
through an unconditioned area, attic or crawl space,
that portion of the vent connector shall be listed
Type B, Type L, or listed vent material having equivalent
insulation qualities.
Exception: Single-wall metal pipe located within the
exterior walls of the building and located in an unconditioned
area other than an attic or a crawl space having
a local 99 percent winter design temperature of
5°F (-15°C) or higher.
[NFPA 54:12.11.2.2]
Vent
connectors for residential-type appliances shall comply
with the following:
-
Vent connectors for listed appliances having
draft hoods, appliances having draft hoods and
equipped with listed conversion burners, and
Category I appliances that are not installed in
attics, crawl spaces, or other unconditioned
areas shall be one of the following:
- Type B or Type L vent material.
- Galvanized sheet steel not less than 0.018 of an inch (0.457 mm) thick.
- Aluminum (1100 or 3003 alloy or equivalent) sheet not less than 0.027 of an inch (0.686 mm) thick.
- Stainless steel sheet not less than 0.012 of an inch (0.305 mm) thick.
- Smooth interior wall metal pipe having resistance to heat and corrosion equal to or greater than that of Section 802.10.1.2(1)(b), Section 802.10.1.2(1)(c), or Section 802.10.1.2(1)(d).
- A listed vent connector.
- Vent connectors shall not be covered with insulation.
Exception: Listed insulated vent connectors shall
be installed in accordance with the manufacturer's
installation instructions.
[NFPA 54:12.11.2.3]
A vent connector for a nonresidential low-heat
appliance shall be a factory-built chimney
section or steel pipe having resistance to heat and
corrosion equivalent to that for the appropriate galvanized
pipe as specified in Table 802.10.1.3. Factory-built chimney sections shall be joined together
in accordance with the chimney manufacturer's
instructions. [NFPA 54:12.11.2.4]
For SI units: 1 inch = 25.4 mm, 1 square inch = 0.000645 m2
| DIAMETER OF CONNECTOR (inches) |
MINIMUM THICKNESS (inches) |
| Less than 6 | 0.019 |
| 6 to less than 10 | 0.023 |
| 10 to 12 inclusive | 0.029 |
| 14 to 16 inclusive | 0.034 |
| Over 16 | 0.056 |
Vent connectors
for medium-heat appliances shall be constructed
of factory-built, medium-heat chimney
sections or steel of a thickness not less than that
specified in Table 802.10.1.4 and shall comply with
the following:
For SI units: 1 inch= 25.4 mm, 1 square inch= 0.000645 m2
- A steel vent connector for an appliance with a vent gas temperature in excess of 1000°F (538°C) measured at the entrance to the connector shall be lined with medium-duty fire brick or the equivalent.
- The lining shall be at least 21/2 inches (64 mm) thick for a vent connector having a diameter or greatest cross-sectional dimension of 18 inches (457 mm) or less.
- The lining shall be at least 41/2 inches (114 mm) thick laid on the 41/2 inches (114 mm) bed for a vent connector having a diameter or greatest cross-sectional dimension greater than 18 inches (457 mm).
- Factory-built chimney sections, if employed, shall be joined together in accordance with the chimney manufacturer's instructions. [NFPA 54:12.11.2.5]
| VENT CONNECTOR SIZE | ||
| DIAMETER (inches) |
AREA (square inches) |
MINIMUM THICKNESS (inches) |
| Up to 14 | Up to 154 | 0.053 |
| Over 14 to 16 | 154 to 201 | 0.067 |
| Over 16 to 18 | 201 to 254 | 0.093 |
| Over 18 | Larger than 254 | 0.123 |
A vent connector
for an appliance with a single draft hood or for a Category
I fan-assisted combustion system appliance shall be sized
and installed in accordance with Section 803.0 or other
approved engineering methods.
[NFPA 54:12.11.3.1]
For a single appliance having
more than one draft hood outlet or flue collar, the
manifold shall be constructed according to the
instructions of the appliance manufacturer. Where
there are no instructions, the manifold shall be
designed and constructed in accordance with
approved engineering practices. As an alternative method, the effective area of the manifold shall equal
the combined area of the flue collars or draft hood
outlets, and the vent connectors shall have a minimum 1 foot (305 mm) rise. [NFPA 54:12.11.3.2]
Where two or more appliances
are connected to a common vent or chimney, each
vent connector shall be sized in accordance with
Section 803.0 or other approved engineering methods.
[NFPA 54:12.11.3.3]
As an alternative method applicable where the appliances are draft hood-equipped, each vent connector shall have an effective area not less than the area of the draft hood outlet of the appliance to which it is connected. [NFPA 54:12.11.3.4]
As an alternative method applicable where the appliances are draft hood-equipped, each vent connector shall have an effective area not less than the area of the draft hood outlet of the appliance to which it is connected. [NFPA 54:12.11.3.4]
Where two or more appliances
are vented through a common vent connector or vent
manifold, the common vent connector or vent manifold
shall be located at the highest level consistent
with available headroom and clearance to combustible
material and sized in accordance with Section 803.0 or other approved engineering methods.
[NFPA 54:12.11.3.5]
As an alternative method applicable only where there are two draft hood-equipped appliances, the effective area of the common vent connector or vent manifold and all junction fittings shall be not less than the area of the larger vent connector plus 50 percent of the area of the smaller flue collar outlet [NFPA 54:12.11.3.6]
As an alternative method applicable only where there are two draft hood-equipped appliances, the effective area of the common vent connector or vent manifold and all junction fittings shall be not less than the area of the larger vent connector plus 50 percent of the area of the smaller flue collar outlet [NFPA 54:12.11.3.6]
Where the size of a
vent connector is increased to overcome installation limitations and obtain connector capacity equal to the
appliance input, the size increase shall be made at the
appliance draft hood outlet.
[NFPA 54:12.11.3.7]
Where two or more openings are provided
into one chimney flue or vent, either of the following
shall apply:
- The openings shall be at different levels.
- The connectors shall be attached to the vertical portion of the chimney or vent at an angle of 45 degrees or less relative to the vertical. [NFPA 54:12.11.4.1]
Where two or
more vent connectors enter a common vent, chimney
flue, or single-wall metal pipe, the smaller connector
shall enter at the highest level consistent with
the available headroom or clearance to combustible
material. [NFPA 54:12.11.4.2]
Vent connectors serving Category
I appliances shall not be connected to a portion
of a mechanical draft system operating under positive
static pressure, such as those serving Category III or
Category IV appliances.
[NFPA 54:12.11.4.3]
Minimum clearances from vent
connectors to combustible material shall comply with
Table 802.7.3.3.
Exception: The clearance between a vent connector and
combustible material shall be permitted to be reduced
where the combustible material is protected as specified
for vent connectors in Table 303.10.1. [NFPA 54:12.11.5]
Joints between sections of connector
piping and connections to flue collars or draft hood outlets
shall be fastened in accordance with one of the following
methods:
- Sheet metal screws.
- Vent connectors of listed vent material assembled and connected to flue collars or draft hood outlets in accordance with the manufacturer's instructions.
- Other approved means. [NFPA 54:12.11.6]
A vent connector shall be installed
without any dips or sags and shall slope upward toward
the vent or chimney at least 1/4 inch per foot (20.8 mm/m).
Exception: Vent connectors attached to a mechanical
draft system installed in accordance with appliance and
the draft system manufacturers' instructions. [NFPA
54:12.11.7]
The length of
vent connectors shall comply with Section 802.10.7.1 or
Section 802.10.7.2.
The maximum
horizontal length of a single-wall connector shall be
75 percent of the height of the chimney or vent except
for engineered systems.
[NFPA 54:12.11.8.1]
The
maximum horizontal length of a Type B double-wall connector shall be 100 percent of the height of the
chimney or vent, except for engineered systems. The
maximum length of an individual connector for a
chimney or vent system serving multiple appliances,
from the appliance outlet to the junction with the
common vent or another connector, shall be 100 percent
of the height of the chimney or vent. [NFPA
54:12.11.8.2]
A vent connector shall be supported
for the design and weight of the material employed to
maintain clearances and prevent physical damage and
separation of joints. [NFPA 54:12.11.9]
Where entering a
flue in a masonry or metal chimney, the vent connector
shall be installed above the extreme bottom to avoid stoppage.
Where a thimble or slip joint is used to facilitate
removal of the connector, the connector shall be attached
to or inserted into the thimble or slip joint to prevent the
connector from falling out. Means shall be employed to
prevent the connector from entering so far as to restrict
the space between its end and the opposite wall of the
chimney flue. [NFPA 54:12.11.10]
The entire length of a vent connector
shall be readily accessible for inspection, cleaning,
and replacement. [NFPA 54:12.11.11]
A vent connector shall not be
connected to a chimney flue serving a fireplace unless
the fireplace flue opening is permanently sealed.
[NFPA 54:12.11.12]
A vent connector shall not pass through a ceiling,
floor, or fire-resistance-rated wall. A single-wall
metal pipe connector shall not pass through an interior
wall.
Exception: Vent connectors made of listed Type B or
Type L vent material and serving listed appliances with
draft hoods and other appliances listed for use with Type
B gas vents that pass through walls or partitions constructed
of combustible material shall be installed with
not less than the listed clearance to combustible material.
Vent
connectors for medium-heat appliances shall not
pass through walls or partitions constructed of combustible
material. [NFPA 54:12.11.13.2]
The vent connectors for
Category II, Category III, and Category IV appliances shall be in accordance with Section 802.4 through Section 802.4.3.
[NFPA 54:12.12]
Vented appliances
shall be installed with draft hoods.
Exception: Dual oven-type combination ranges; incinerators;
direct-vent appliances; fan-assisted combustion system appliances;
appliances requiring chimney draft for operation; single
firebox boilers equipped with conversion burners with inputs exceeding 400 000 Btu/h (117 kW); appliances
equipped with blast, power, or pressure burners that are not
listed for use with draft hoods; and appliances designed for
forced venting.
A draft hood supplied with or
forming a part of listed vented appliances shall be
installed without alteration, exactly as furnished and specified
by the appliance manufacturer.
[NFPA 54:12.13.2]
Where a draft hood is not supplied by the appliance manufacturer where one is required, a draft hood shall be installed, be of a listed or approved type, and, in the absence of other instructions, be of the same size as the appliance flue collar. Where a draft hood is required with a conversion burner, it shall be of a listed or approved type. [NFPA 54:12.13.2.1]
Where a draft hood of special design is needed or preferable, the installation shall be approved and in accordance with the recommendations of the appliance manufacturer. [NFPA 54:12.13.2.2]
Where a draft hood is not supplied by the appliance manufacturer where one is required, a draft hood shall be installed, be of a listed or approved type, and, in the absence of other instructions, be of the same size as the appliance flue collar. Where a draft hood is required with a conversion burner, it shall be of a listed or approved type. [NFPA 54:12.13.2.1]
Where a draft hood of special design is needed or preferable, the installation shall be approved and in accordance with the recommendations of the appliance manufacturer. [NFPA 54:12.13.2.2]
Where a draft control
device is part of the appliance or is supplied by the
appliance manufacturer, it shall be installed in accordance
with the manufacturer's instructions. In the
absence of manufacturer's instructions, the device shall
be attached to the flue collar of the appliance or as near
to the appliance as practical.
[NFPA 54:12.13.3]
Appliances requiring
controlled chimney draft shall be permitted to be
equipped with listed double-acting barometric draft regulators
installed and adjusted in accordance with the
manufacturer's installation instructions.
[NFPA 54:12.13.4]
Draft hoods and barometric draft
regulators shall be installed in the same room or enclosure
as the appliance in such a manner as to prevent a
difference in pressure between the hood or regulator and
the combustion air supply.
[NFPA 54:12.13.5]
Draft hoods and draft regulators
shall be installed in the position for which they were
designed with reference to the horizontal and vertical
planes and shall be located so that the relief opening is
not obstructed by a part of the appliance or adjacent construction.
The appliance and its draft hood shall be
located so that the relief opening is accessible for checking
vent operation. [NFPA 54:12.13.6]
A draft hood shall be located so
that its relief opening is not less than 6 inches (152 mm)
from a surface except that of the appliance it serves and
the venting system to which the draft hood is connected.
Where a greater or lesser clearance is indicated on the
appliance label, the clearance shall not be less than that
specified on the label. Such clearances shall not be
reduced. [NFPA 54:12.13.7]
A manually operated
damper shall not be placed in an appliance vent connector.
Fixed baffles shall not be classified as manually operated
dampers. [NFPA 54:12.14]
Devices that retard the flow of vent
gases shall not be installed in a vent connector, chimney, or
vent. The following shall not be considered as obstructions:
- Draft regulators and safety controls specifically listed for installation in venting systems and installed in accordance with the manufacturer's installation instructions.
- Approved draft regulators and safety controls designed and installed in accordance with approved engineering methods.
- Listed heat reclaimers and automatically operated vent dampers installed in accordance with the manufacturer's installation instructions.
- Vent dampers serving listed appliances installed in accordance with Section 803.1 or Section 803.2 or other approved engineering methods.
- Approved economizers, heat reclaimers, and recuperators installed in venting systems of appliances not required to be equipped with draft hoods, provided the appliance manufacturer's installation instructions cover the installation of such a device in the venting system and performance in accordance with Section 802.3 and Section 802.3.1 is obtained. [NFPA 54:12.16]
An automatically operated vent damper shall be of a listed type.
[NFPA 54:12.15]
Automatically operated vent dampers
for oil-fired appliances shall comply with UL 17. The
automatic damper control shall comply with UL 378.
Table 803.1.2(1) through
Table 803.1.2(6)
shall not be used where obstructions are installed in the venting
system. The installation of vents serving listed appliances
with vent dampers shall be in accordance with the appliance
manufacturer's installation instructions or in accordance with
the following:
- The maximum capacity of the vent system shall be determined using the NAT Max column.
- The minimum capacity shall be determined as though the appliance were a fan-assisted appliance, using the FAN Min column to determine the minimum capacity of the vent system. Where the corresponding "FAN Min" is "NA", the vent configuration shall not be permitted and an alternative venting configuration shall be utilized. [NFPA 54:13.1.1]
Where the vent size determined
from the tables is smaller than the appliance draft
hood outlet or flue collar, the use of the smaller size shall
be permitted provided that the installation is in accordance
with the following requirements:
- The total vent height (H) is not less than 10 feet (3048 mm).
- Vents for appliance draft hood outlets or flue collars 12 inches (305 mm) in diameter or smaller are not reduced more than one table size.
- Vents for appliance draft hood outlets or flue collars exceeding 12 inches (305 mm) in diameter are not reduced more than two table sizes.
- The maximum capacity listed in the tables for a fan-assisted appliance is reduced by 10 percent (0.90 x maximum table capacity).
- The draft hood outlet exceeds 4 inches (102 mm) in diameter. A 3 inch (76 mm) diameter vent shall not be connected to a 4 inch (102 mm) diameter draft hood outlet. This provision shall not apply to fan-assisted appliances. [NFPA 54:13.1.2]
Single-appliance venting configurations
with zero (0) lateral lengths in Table 803.1.2(1),
Table 803.1.2(2), and
Table 803.1.2(5) shall not have
elbows in the venting system.
Single-appliance venting
with lateral length, include two 90 degree elbows. For
each additional elbow up to and including 45 degrees,
the maximum capacity listed in the venting tables shall
be reduced by 5 percent. For each additional elbow
greater than 45 degrees up to and including 90 degrees,
the maximum capacity listed in the venting tables shall
be reduced by 10 percent. Where multiple offsets occur
in a vent, the total lateral length of all offsets combined
shall not exceed that specified in Table 803.1.2(1)
through Table 803.1.2(5).
[NFPA 54:13.1.3]
FIGURE 803.1.2(6)
RANGE OF WINTER DESIGN TEMPERATURES USED IN ANALYZING EXTERIOR MASONRY CHIMNEYS IN THE UNITED STATES
[NFPA 54: FIGURE F.2.4]
For SI units: 1 inch = 25.4 mm, 1 foot = 304.8 mm, 1000 British thermal units per hour = 0.293 kW, 1 square inch = 0.000645 m2
* NA: Not applicable.
For SI units: 1 inch = 25.4 mm, 1 foot = 304.8 mm, 1000 British thermal units per hour = 0.293 kW, 1 square inch = 0.000645 m2
For SI units: 1 inch = 25.4 mm, 1 foot = 304.8 mm, 1000 British thermal units per hour = 0.293 kW, 1 square inch = 0.000645 m2
For SI units: 1 inch = 25.4 mm, 1 foot = 304.8 mm, 1000 British thermal units per hour = 0.293 kW, 1 square inch = 0.000645 m2
* NA: Not applicable.
For SI units: 1 inch = 25.4 mm, 1 foot = 304.8 mm, 1000 British thermal units per hour = 0.293 kW, 1 square inch = 0.000645 m2
* NA: Not applicable.
For SI units: 1 inch = 25.4 mm, 1 foot = 304.8 mm, 1000 British thermal units per hour = 0.293 kW, 1 square inch = 0.000645 m2
* NA: Not applicable.
For SI units: 1 inch = 25.4 mm, 1 foot = 304.8 mm, 1000 British thermal units per hour = 0.293 kW, 1 square inch = 0.000645 m2
* NA: Not applicable.
For SI units: 1 inch = 25.4 mm, 1 foot = 304.8 mm, 1000 British thermal units per hour = 0.293 kW, 1 square inch = 0.000645 m2
* NA: Not applicable.
For SI units: 1 inch = 25.4 mm, 1 foot = 304.8 mm, 1000 British thermal units per hour = 0.293 kW, 1 square inch = 0.000645 m2
* NA: Not applicable.
For SI units: 1 inch = 25.4 mm, 1 foot = 304.8 mm, 1000 British thermal units per hour = 0.293 kW, 1 square inch = 0.000645 m2
* NA: Not applicable.
For SI units: 1 inch = 25.4 mm, 1 foot = 304.8 mm, 1000 British thermal units per hour = 0.293 kW, 1 square inch = 0.000645 m2,
°C = (°F-32)/1.8
Notes:
99% Winter Design Temperatures for the Contiguous United States
This map is a necessarily generalized guide to temperatures in the contiguous United States. Temperatures shown for areas such as mountainous regions and large urban centers may not be accurate. The data used to develop this map are from the 1993 ASHRAE Handbook - Fundamentals (Chapter 24, Table 1: Climate Conditions for the United States).
For 99% winter design temperatures in Alaska, consult the ASHRAE Handbook - Fundamentals.
99% winter design temperatures for Hawaii are greater than 37°F.
For SI units: °C = (°F-32)/1.8
This map is a necessarily generalized guide to temperatures in the contiguous United States. Temperatures shown for areas such as mountainous regions and large urban centers may not be accurate. The data used to develop this map are from the 1993 ASHRAE Handbook - Fundamentals (Chapter 24, Table 1: Climate Conditions for the United States).
For 99% winter design temperatures in Alaska, consult the ASHRAE Handbook - Fundamentals.
99% winter design temperatures for Hawaii are greater than 37°F.
For SI units: °C = (°F-32)/1.8
RANGE OF WINTER DESIGN TEMPERATURES USED IN ANALYZING EXTERIOR MASONRY CHIMNEYS IN THE UNITED STATES
[NFPA 54: FIGURE F.2.4]
| NUMBER OF APPLIANCES: | SINGLE | |||||||||||||||
| APPLIANCE TYPE: | CATEGORY I | |||||||||||||||
| APPLIANCE VENT CONNECTION: | CONNECTED DIRECTLY TO VENT | |||||||||||||||
| VENT DIAMETER - D (inch) | ||||||||||||||||
| 3 | 4 | 5 | 6 | 7 | ||||||||||||
| APPLIANCE INPUT RATING IN THOUSANDS OF BTU PER HOUR | ||||||||||||||||
| HEIGHT H (feet) |
LATERAL L (feet) |
FAN | NAT | FAN | NAT | FAN | NAT | FAN | NAT | FAN | NAT | |||||
| Min | Max | Max | Min | Max | Max | Min | Max | Max | Min | Max | Max | Min | Max | Max | ||
| 6 | 0 | 0 | 78 | 46 | 0 | 152 | 86 | 0 | 251 | 141 | 0 | 375 | 205 | 0 | 524 | 285 |
| 2 | 13 | 51 | 36 | 18 | 97 | 67 | 27 | 157 | 105 | 32 | 232 | 157 | 44 | 321 | 217 | |
| 4 | 21 | 49 | 34 | 30 | 94 | 64 | 39 | 153 | 103 | 50 | 227 | 153 | 66 | 316 | 211 | |
| 6 | 25 | 46 | 32 | 36 | 91 | 61 | 47 | 149 | 100 | 59 | 223 | 149 | 78 | 310 | 205 | |
| 8 | 0 | 0 | 84 | 50 | 0 | 165 | 94 | 0 | 276 | 155 | 0 | 415 | 235 | 0 | 583 | 320 |
| 2 | 12 | 57 | 40 | 16 | 109 | 75 | 25 | 178 | 120 | 28 | 263 | 180 | 42 | 365 | 247 | |
| 5 | 23 | 53 | 38 | 32 | 103 | 71 | 42 | 171 | 115 | 53 | 255 | 173 | 70 | 356 | 237 | |
| 8 | 28 | 49 | 35 | 39 | 98 | 66 | 51 | 164 | 109 | 64 | 247 | 165 | 84 | 347 | 227 | |
| 10 | 0 | 0 | 88 | 53 | 0 | 175 | 100 | 0 | 295 | 166 | 0 | 447 | 255 | 0 | 631 | 345 |
| 2 | 12 | 61 | 42 | 17 | 118 | 81 | 23 | 194 | 129 | 26 | 289 | 195 | 40 | 402 | 273 | |
| 5 | 23 | 57 | 40 | 32 | 113 | 77 | 41 | 187 | 124 | 52 | 280 | 188 | 68 | 392 | 263 | |
| 10 | 30 | 51 | 36 | 41 | 104 | 70 | 54 | 176 | 115 | 67 | 267 | 175 | 88 | 376 | 245 | |
| 15 | 0 | 0 | 94 | 58 | 0 | 191 | 112 | 0 | 327 | 187 | 0 | 502 | 285 | 0 | 716 | 390 |
| 2 | 11 | 69 | 48 | 15 | 136 | 93 | 20 | 226 | 150 | 22 | 339 | 225 | 38 | 475 | 316 | |
| 5 | 22 | 65 | 45 | 30 | 130 | 87 | 39 | 219 | 142 | 49 | 330 | 217 | 64 | 463 | 300 | |
| 10 | 29 | 59 | 41 | 40 | 121 | 82 | 51 | 206 | 135 | 64 | 315 | 208 | 84 | 445 | 288 | |
| 15 | 35 | 53 | 37 | 48 | 112 | 76 | 61 | 195 | 128 | 76 | 301 | 198 | 98 | 429 | 275 | |
| 20 | 0 | 0 | 97 | 61 | 0 | 202 | 119 | 0 | 349 | 202 | 0 | 540 | 307 | 0 | 776 | 430 |
| 2 | 10 | 75 | 51 | 14 | 149 | 100 | 18 | 250 | 166 | 20 | 377 | 249 | 33 | 531 | 346 | |
| 5 | 21 | 71 | 48 | 29 | 143 | 96 | 38 | 242 | 160 | 47 | 367 | 241 | 62 | 519 | 337 | |
| 10 | 28 | 64 | 44 | 38 | 133 | 89 | 50 | 229 | 150 | 62 | 351 | 228 | 81 | 499 | 321 | |
| 15 | 34 | 58 | 40 | 46 | 124 | 84 | 59 | 217 | 142 | 73 | 337 | 217 | 94 | 481 | 308 | |
| 20 | 48 | 52 | 35 | 55 | 116 | 78 | 69 | 206 | 134 | 84 | 322 | 206 | 107 | 464 | 295 | |
| 30 | 0 | 0 | 100 | 64 | 0 | 213 | 128 | 0 | 374 | 220 | 0 | 587 | 336 | 0 | 853 | 475 |
| 2 | 9 | 81 | 56 | 13 | 166 | 112 | 14 | 283 | 185 | 18 | 432 | 280 | 27 | 613 | 394 | |
| 5 | 21 | 77 | 54 | 28 | 160 | 108 | 36 | 275 | 176 | 45 | 421 | 273 | 58 | 600 | 385 | |
| 10 | 27 | 70 | 50 | 37 | 150 | 102 | 48 | 262 | 171 | 59 | 405 | 261 | 77 | 580 | 371 | |
| 15 | 33 | 64 | NA | 44 | 141 | 96 | 57 | 249 | 163 | 70 | 389 | 249 | 90 | 560 | 357 | |
| 20 | 56 | 58 | NA | 53 | 132 | 90 | 66 | 237 | 154 | 80 | 374 | 237 | 102 | 542 | 343 | |
| 30 | NA | NA | NA | 73 | 113 | NA | 88 | 214 | NA | 104 | 346 | 219 | 131 | 507 | 321 | |
| 50 | 0 | 0 | 101 | 67 | 0 | 216 | 134 | 0 | 397 | 232 | 0 | 633 | 363 | 0 | 932 | 518 |
| 2 | 8 | 86 | 61 | 11 | 183 | 122 | 14 | 320 | 206 | 15 | 497 | 314 | 22 | 715 | 445 | |
| 5 | 20 | 82 | NA | 27 | 177 | 119 | 35 | 312 | 200 | 43 | 487 | 308 | 55 | 702 | 438 | |
| 10 | 26 | 76 | NA | 35 | 168 | 114 | 45 | 299 | 190 | 56 | 471 | 298 | 73 | 681 | 426 | |
| 15 | 59 | 70 | NA | 42 | 158 | NA | 54 | 287 | 180 | 66 | 455 | 288 | 85 | 662 | 413 | |
| 20 | NA | NA | NA | 50 | 149 | NA | 63 | 275 | 169 | 76 | 440 | 278 | 97 | 642 | 401 | |
| 30 | NA | NA | NA | 69 | 131 | NA | 84 | 250 | NA | 99 | 410 | 259 | 123 | 605 | 376 | |
| 100 | 0 | NA | NA | NA | 0 | 218 | NA | 0 | 407 | NA | 0 | 665 | 400 | 0 | 997 | 560 |
| 2 | NA | NA | NA | 10 | 194 | NA | 12 | 354 | NA | 13 | 566 | 375 | 18 | 831 | 510 | |
| 5 | NA | NA | NA | 26 | 189 | NA | 33 | 347 | NA | 40 | 557 | 369 | 52 | 820 | 504 | |
| 10 | NA | NA | NA | 33 | 182 | NA | 43 | 335 | NA | 53 | 542 | 361 | 68 | 801 | 493 | |
| 15 | NA | NA | NA | 40 | 174 | NA | 50 | 321 | NA | 62 | 528 | 353 | 80 | 782 | 482 | |
| 20 | NA | NA | NA | 47 | 166 | NA | 59 | 311 | NA | 71 | 513 | 344 | 90 | 763 | 471 | |
| 30 | NA | NA | NA | NA | NA | NA | 78 | 290 | NA | 92 | 483 | NA | 115 | 726 | 449 | |
| 50 | NA | NA | NA | NA | NA | NA | NA | NA | NA | 147 | 428 | NA | 180 | 651 | 405 | |
* NA: Not applicable.
| NUMBER OF APPLIANCES: | SINGLE | |||||||||||||||
| APPLIANCE TYPE: | CATEGORY I | |||||||||||||||
| APPLIANCE VENT CONNECTION: | CONNECTED DIRECTLY TO VENT | |||||||||||||||
| VENT DIAMETER - D (inch) | ||||||||||||||||
| 8 | 9 | 10 | 12 | 14 | ||||||||||||
| APPLIANCE INPUT RATING IN THOUSANDS OF BTU PER HOUR | ||||||||||||||||
| HEIGHT H (feet) |
LATERAL L (feet) |
FAN | NAT | FAN | NAT | FAN | NAT | FAN | NAT | FAN | NAT | |||||
| Min | Max | Max | Min | Max | Max | Min | Max | Max | Min | Max | Max | Min | Max | Max | ||
| 6 | 0 | 0 | 698 | 370 | 0 | 897 | 470 | 0 | 1121 | 570 | 0 | 1645 | 850 | 0 | 2267 | 1170 |
| 2 | 53 | 425 | 285 | 63 | 543 | 370 | 75 | 675 | 455 | 103 | 982 | 650 | 138 | 1346 | 890 | |
| 4 | 79 | 419 | 279 | 93 | 536 | 362 | 110 | 668 | 445 | 147 | 975 | 640 | 191 | 1338 | 880 | |
| 6 | 93 | 413 | 273 | 110 | 530 | 354 | 128 | 661 | 435 | 171 | 967 | 630 | 219 | 1330 | 870 | |
| 8 | 0 | 0 | 780 | 415 | 0 | 1006 | 537 | 0 | 1261 | 660 | 0 | 1858 | 970 | 0 | 2571 | 1320 |
| 2 | 50 | 483 | 322 | 60 | 619 | 418 | 71 | 770 | 515 | 98 | 1124 | 745 | 130 | 1543 | 1020 | |
| 5 | 83 | 473 | 313 | 99 | 607 | 407 | 115 | 758 | 503 | 154 | 1110 | 733 | 199 | 1528 | 1010 | |
| 8 | 99 | 463 | 303 | 117 | 596 | 396 | 137 | 746 | 490 | 180 | 1097 | 720 | 231 | 1514 | 1000 | |
| 10 | 0 | 0 | 847 | 450 | 0 | 1096 | 585 | 0 | 1377 | 720 | 0 | 2036 | 1060 | 0 | 2825 | 1450 |
| 2 | 48 | 533 | 355 | 57 | 684 | 457 | 68 | 852 | 560 | 93 | 1244 | 850 | 124 | 1713 | 1130 | |
| 5 | 81 | 522 | 346 | 95 | 671 | 446 | 112 | 839 | 547 | 149 | 1229 | 829 | 192 | 1696 | 1105 | |
| 10 | 104 | 504 | 330 | 122 | 651 | 427 | 142 | 817 | 525 | 187 | 1204 | 795 | 238 | 1669 | 1080 | |
| 15 | 0 | 0 | 970 | 525 | 0 | 1263 | 682 | 0 | 1596 | 840 | 0 | 2380 | 1240 | 0 | 3323 | 1720 |
| 2 | 45 | 633 | 414 | 53 | 815 | 544 | 63 | 1019 | 675 | 86 | 1495 | 985 | 114 | 2062 | 1350 | |
| 5 | 76 | 620 | 403 | 90 | 800 | 529 | 105 | 1003 | 660 | 140 | 1476 | 967 | 182 | 2041 | 1327 | |
| 10 | 99 | 600 | 386 | 116 | 777 | 507 | 135 | 977 | 635 | 177 | 1446 | 936 | 227 | 2009 | 1289 | |
| 15 | 115 | 580 | 373 | 134 | 755 | 491 | 155 | 953 | 610 | 202 | 1418 | 905 | 257 | 1976 | 1250 | |
| 20 | 0 | 0 | 1057 | 575 | 0 | 1384 | 752 | 0 | 1756 | 930 | 0 | 2637 | 1350 | 0 | 3701 | 1900 |
| 2 | 41 | 711 | 470 | 50 | 917 | 612 | 59 | 1150 | 755 | 81 | 1694 | 1100 | 107 | 2343 | 1520 | |
| 5 | 73 | 697 | 460 | 86 | 902 | 599 | 101 | 1133 | 738 | 135 | 1674 | 1079 | 174 | 2320 | 1498 | |
| 10 | 95 | 675 | 443 | 112 | 877 | 576 | 130 | 1105 | 710 | 172 | 1641 | 1045 | 220 | 2282 | 1460 | |
| 15 | 111 | 654 | 427 | 129 | 853 | 557 | 150 | 1078 | 688 | 195 | 1609 | 1018 | 248 | 2245 | 1425 | |
| 20 | 125 | 634 | 410 | 145 | 830 | 537 | 167 | 1052 | 665 | 217 | 1578 | 990 | 273 | 2210 | 1390 | |
| 30 | 0 | 0 | 1173 | 650 | 0 | 1548 | 855 | 0 | 1977 | 1060 | 0 | 3004 | 1550 | 0 | 4252 | 2170 |
| 2 | 33 | 826 | 535 | 42 | 1072 | 700 | 54 | 1351 | 865 | 74 | 2004 | 1310 | 98 | 2786 | 1800 | |
| 5 | 69 | 811 | 524 | 82 | 1055 | 688 | 96 | 1332 | 851 | 127 | 1981 | 1289 | 164 | 2759 | 1775 | |
| 10 | 91 | 788 | 507 | 107 | 1028 | 668 | 125 | 1301 | 829 | 164 | 1944 | 1254 | 209 | 2716 | 1733 | |
| 15 | 105 | 765 | 490 | 124 | 1002 | 648 | 143 | 1272 | 807 | 187 | 1908 | 1220 | 237 | 2674 | 1692 | |
| 20 | 119 | 743 | 473 | 139 | 977 | 628 | 160 | 1243 | 784 | 207 | 1873 | 1185 | 260 | 2633 | 1650 | |
| 30 | 149 | 702 | 444 | 171 | 929 | 594 | 195 | 1189 | 745 | 246 | 1807 | 1130 | 305 | 2555 | 1585 | |
| 50 | 0 | 0 | 1297 | 708 | 0 | 1730 | 952 | 0 | 2231 | 1195 | 0 | 3441 | 1825 | 0 | 4934 | 2550 |
| 2 | 26 | 975 | 615 | 33 | 1276 | 813 | 41 | 1620 | 1010 | 66 | 2431 | 1513 | 86 | 3409 | 2125 | |
| 5 | 65 | 960 | 605 | 77 | 1259 | 798 | 90 | 1600 | 996 | 118 | 2406 | 1495 | 151 | 3380 | 2102 | |
| 10 | 86 | 935 | 589 | 101 | 1230 | 773 | 118 | 1567 | 972 | 154 | 2366 | 1466 | 196 | 3332 | 2064 | |
| 15 | 100 | 911 | 572 | 117 | 1203 | 747 | 136 | 1536 | 948 | 177 | 2327 | 1437 | 222 | 3285 | 2026 | |
| 20 | 113 | 888 | 556 | 131 | 1176 | 722 | 151 | 1505 | 924 | 195 | 2288 | 1408 | 244 | 3239 | 1987 | |
| 30 | 141 | 844 | 522 | 161 | 1125 | 670 | 183 | 1446 | 876 | 232 | 2214 | 1349 | 287 | 3150 | 1910 | |
| 100 | 0 | 0 | 1411 | 770 | 0 | 1908 | 1040 | 0 | 2491 | 1310 | 0 | 3925 | 2050 | 0 | 5729 | 2950 |
| 2 | 21 | 1155 | 700 | 25 | 1536 | 935 | 30 | 1975 | 1170 | 44 | 3027 | 1820 | 72 | 4313 | 2550 | |
| 5 | 60 | 1141 | 692 | 71 | 1519 | 926 | 82 | 1955 | 1159 | 107 | 3002 | 1803 | 136 | 4282 | 2531 | |
| 10 | 80 | 1118 | 679 | 94 | 1492 | 910 | 108 | 1923 | 1142 | 142 | 2961 | 1775 | 180 | 4231 | 2500 | |
| 15 | 93 | 1095 | 666 | 109 | 1465 | 895 | 126 | 1892 | 1124 | 163 | 2920 | 1747 | 206 | 4182 | 2469 | |
| 20 | 105 | 1073 | 653 | 122 | 1438 | 880 | 141 | 1861 | 1107 | 181 | 2880 | 1719 | 226 | 4133 | 2438 | |
| 30 | 131 | 1029 | 627 | 149 | 1387 | 849 | 170 | 1802 | 1071 | 215 | 2803 | 1663 | 265 | 4037 | 2375 | |
| 50 | 197 | 944 | 575 | 217 | 1288 | 787 | 241 | 1688 | 1000 | 292 | 2657 | 1550 | 350 | 3856 | 2250 | |
| NUMBER OF APPLIANCES: | SINGLE | |||||||||||||||
| APPLIANCE TYPE: | CATEGORY I | |||||||||||||||
| APPLIANCE VENT CONNECTION: | CONNECTED DIRECTLY TO VENT | |||||||||||||||
| VENT DIAMETER - D (inch) | ||||||||||||||||
| 16 | 18 | 20 | 22 | 24 | ||||||||||||
| APPLIANCE INPUT RATING IN THOUSANDS OF BTU PER HOUR | ||||||||||||||||
| HEIGHT H (feet) |
LATERAL L (feet) |
FAN | NAT | FAN | NAT | FAN | NAT | FAN | NAT | FAN | NAT | |||||
| Min | Max | Max | Min | Max | Max | Min | Max | Max | Min | Max | Max | Min | Max | Max | ||
| 6 | 0 | 0 | 2983 | 1530 | 0 | 3802 | 1960 | 0 | 4721 | 2430 | 0 | 5737 | 2950 | 0 | 6853 | 3520 |
| 2 | 178 | 1769 | 1170 | 225 | 2250 | 1480 | 296 | 2782 | 1850 | 360 | 3377 | 2220 | 426 | 4030 | 2670 | |
| 4 | 242 | 1761 | 1160 | 300 | 2242 | 1475 | 390 | 2774 | 1835 | 469 | 3370 | 2215 | 555 | 4023 | 2660 | |
| 6 | 276 | 1753 | 1150 | 341 | 2235 | 1470 | 437 | 2767 | 1820 | 523 | 3363 | 2210 | 618 | 4017 | 2650 | |
| 8 | 0 | 0 | 3399 | 1740 | 0 | 4333 | 2220 | 0 | 5387 | 2750 | 0 | 6555 | 3360 | 0 | 7838 | 4010 |
| 2 | 168 | 2030 | 1340 | 212 | 2584 | 1700 | 278 | 3196 | 2110 | 336 | 3882 | 2560 | 401 | 4634 | 3050 | |
| 5 | 251 | 2013 | 1330 | 311 | 2563 | 1685 | 398 | 3180 | 2090 | 476 | 3863 | 2545 | 562 | 4612 | 3040 | |
| 8 | 289 | 2000 | 1320 | 354 | 2552 | 1670 | 450 | 3163 | 2070 | 537 | 3850 | 2530 | 630 | 4602 | 3030 | |
| 10 | 0 | 0 | 3742 | 1925 | 0 | 4782 | 2450 | 0 | 5955 | 3050 | 0 | 7254 | 3710 | 0 | 8682 | 4450 |
| 2 | 161 | 2256 | 1480 | 202 | 2868 | 1890 | 264 | 3556 | 2340 | 319 | 4322 | 2840 | 378 | 5153 | 3390 | |
| 5 | 243 | 2238 | 1461 | 300 | 2849 | 1871 | 382 | 3536 | 2318 | 458 | 4301 | 2818 | 540 | 5132 | 3371 | |
| 10 | 298 | 2209 | 1430 | 364 | 2818 | 1840 | 459 | 3504 | 2280 | 546 | 4268 | 2780 | 641 | 5099 | 3340 | |
| 15 | 0 | 0 | 4423 | 2270 | 0 | 5678 | 2900 | 0 | 7099 | 3620 | 0 | 8665 | 4410 | 0 | 10393 | 5300 |
| 2 | 147 | 2719 | 1770 | 186 | 3467 | 2260 | 239 | 4304 | 2800 | 290 | 5232 | 3410 | 346 | 6251 | 4080 | |
| 5 | 229 | 2696 | 1748 | 283 | 3442 | 2235 | 355 | 4278 | 2777 | 426 | 5204 | 3385 | 501 | 6222 | 4057 | |
| 10 | 283 | 2659 | 1712 | 346 | 3402 | 2193 | 432 | 4234 | 2739 | 510 | 5159 | 3343 | 599 | 6175 | 4019 | |
| 15 | 318 | 2623 | 1675 | 385 | 3363 | 2150 | 479 | 4192 | 2700 | 564 | 5115 | 3300 | 665 | 6129 | 3980 | |
| 20 | 0 | 0 | 4948 | 2520 | 0 | 6376 | 3250 | 0 | 7988 | 4060 | 0 | 9785 | 4980 | 0 | 11753 | 6000 |
| 2 | 139 | 3097 | 2000 | 175 | 3955 | 2570 | 220 | 4916 | 3200 | 269 | 5983 | 3910 | 321 | 7154 | 4700 | |
| 5 | 219 | 3071 | 1978 | 270 | 3926 | 2544 | 337 | 4885 | 3174 | 403 | 5950 | 3880 | 475 | 7119 | 4662 | |
| 10 | 273 | 3029 | 1940 | 334 | 3880 | 2500 | 413 | 4835 | 3130 | 489 | 5896 | 3830 | 573 | 7063 | 4600 | |
| 15 | 306 | 2988 | 1910 | 372 | 3835 | 2465 | 459 | 4786 | 3090 | 541 | 5844 | 3795 | 631 | 7007 | 4575 | |
| 20 | 335 | 2948 | 1880 | 404 | 3791 | 2430 | 495 | 4737 | 3050 | 585 | 5792 | 3760 | 689 | 6953 | 4550 | |
| 30 | 0 | 0 | 5725 | 2920 | 0 | 7420 | 3770 | 0 | 9341 | 4750 | 0 | 11483 | 5850 | 0 | 13848 | 7060 |
| 2 | 127 | 3696 | 2380 | 159 | 4734 | 3050 | 199 | 5900 | 3810 | 241 | 7194 | 4650 | 285 | 8617 | 5600 | |
| 5 | 206 | 3666 | 2350 | 252 | 4701 | 3020 | 312 | 5863 | 3783 | 373 | 7155 | 4622 | 439 | 8574 | 5552 | |
| 10 | 259 | 3617 | 2300 | 316 | 4647 | 2970 | 386 | 5803 | 3739 | 456 | 7090 | 4574 | 535 | 8505 | 5471 | |
| 15 | 292 | 3570 | 2250 | 354 | 4594 | 2920 | 431 | 5744 | 3695 | 507 | 7026 | 4527 | 590 | 8437 | 5391 | |
| 20 | 319 | 3523 | 2200 | 384 | 4542 | 2870 | 467 | 5686 | 3650 | 548 | 6964 | 4480 | 639 | 8370 | 5310 | |
| 30 | 369 | 3433 | 2130 | 440 | 4442 | 2785 | 540 | 5574 | 3565 | 635 | 6842 | 4375 | 739 | 8239 | 5225 | |
| 50 | 0 | 0 | 6711 | 3440 | 0 | 8774 | 4460 | 0 | 11129 | 5635 | 0 | 13767 | 6940 | 0 | 16694 | 8430 |
| 2 | 113 | 4554 | 2840 | 141 | 5864 | 3670 | 171 | 7339 | 4630 | 209 | 8980 | 5695 | 251 | 10788 | 6860 | |
| 5 | 191 | 4520 | 2813 | 234 | 5826 | 3639 | 283 | 7295 | 4597 | 336 | 8933 | 5654 | 394 | 10737 | 6818 | |
| 10 | 243 | 4464 | 2767 | 295 | 5763 | 3585 | 355 | 7224 | 4542 | 419 | 8855 | 5585 | 491 | 10652 | 6749 | |
| 15 | 274 | 4409 | 2721 | 330 | 5701 | 3534 | 396 | 7155 | 4511 | 465 | 8779 | 5546 | 542 | 10570 | 6710 | |
| 20 | 300 | 4356 | 2675 | 361 | 5641 | 3481 | 433 | 7086 | 4479 | 506 | 8704 | 5506 | 586 | 10488 | 6670 | |
| 30 | 347 | 4253 | 2631 | 412 | 5523 | 3431 | 494 | 6953 | 4421 | 577 | 8557 | 5444 | 672 | 10328 | 6603 | |
| 100 | 0 | 0 | 7914 | 4050 | 0 | 10485 | 5300 | 0 | 13454 | 6700 | 0 | 16817 | 8600 | 0 | 20578 | 10300 |
| 2 | 95 | 5834 | 3500 | 120 | 7591 | 4600 | 138 | 9577 | 5800 | 169 | 11803 | 7200 | 204 | 14264 | 8800 | |
| 5 | 172 | 5797 | 3475 | 208 | 7548 | 4566 | 245 | 9528 | 5769 | 293 | 11748 | 7162 | 341 | 14204 | 8756 | |
| 10 | 223 | 5737 | 3434 | 268 | 7478 | 4509 | 318 | 9447 | 5717 | 374 | 11658 | 7100 | 436 | 14105 | 8683 | |
| 15 | 252 | 5678 | 3392 | 304 | 7409 | 4451 | 358 | 9367 | 5665 | 418 | 11569 | 7037 | 487 | 14007 | 8610 | |
| 20 | 277 | 5619 | 3351 | 330 | 7341 | 4394 | 387 | 9289 | 5613 | 452 | 11482 | 6975 | 523 | 13910 | 8537 | |
| 30 | 319 | 5505 | 3267 | 378 | 7209 | 4279 | 446 | 9136 | 5509 | 514 | 11310 | 6850 | 592 | 13720 | 8391 | |
| 50 | 415 | 5289 | 3100 | 486 | 6956 | 4050 | 572 | 8841 | 5300 | 659 | 10979 | 6600 | 752 | 13354 | 8100 | |
| NUMBER OF APPLIANCES: | SINGLE | |||||||||||||||
| APPLIANCE TYPE: | CATEGORY I | |||||||||||||||
| APPLIANCE VENT CONNECTION: | SINGLE-WALL METAL CONNECTOR | |||||||||||||||
| VENT DIAMETER - D (inch) | ||||||||||||||||
| 3 | 4 | 5 | 6 | 7 | ||||||||||||
| APPLIANCE INPUT RATING IN THOUSANDS OF BTU PER HOUR | ||||||||||||||||
| HEIGHT H (feet) |
LATERAL L (feet) |
FAN | NAT | FAN | NAT | FAN | NAT | FAN | NAT | FAN | NAT | |||||
| Min | Max | Max | Min | Max | Max | Min | Max | Max | Min | Max | Max | Min | Max | Max | ||
| 6 | 0 | 38 | 77 | 45 | 59 | 151 | 85 | 85 | 249 | 140 | 126 | 373 | 204 | 165 | 522 | 284 |
| 2 | 39 | 51 | 36 | 60 | 96 | 66 | 85 | 156 | 104 | 123 | 231 | 156 | 159 | 320 | 213 | |
| 4 | NA | NA | 33 | 74 | 92 | 63 | 102 | 152 | 102 | 146 | 225 | 152 | 187 | 313 | 208 | |
| 6 | NA | NA | 31 | 83 | 89 | 60 | 114 | 147 | 99 | 163 | 220 | 148 | 207 | 307 | 203 | |
| 8 | 0 | 37 | 83 | 50 | 58 | 164 | 93 | 83 | 273 | 154 | 123 | 412 | 234 | 161 | 580 | 319 |
| 2 | 39 | 56 | 39 | 59 | 108 | 75 | 83 | 176 | 119 | 121 | 261 | 179 | 155 | 263 | 246 | |
| 5 | NA | NA | 37 | 77 | 102 | 69 | 107 | 168 | 114 | 151 | 252 | 171 | 193 | 352 | 235 | |
| 8 | NA | NA | 33 | 90 | 95 | 64 | 122 | 161 | 107 | 175 | 243 | 163 | 223 | 342 | 225 | |
| 10 | 0 | 37 | 87 | 53 | 57 | 174 | 99 | 82 | 293 | 165 | 120 | 444 | 254 | 158 | 628 | 344 |
| 2 | 39 | 61 | 41 | 59 | 117 | 80 | 82 | 193 | 128 | 119 | 287 | 194 | 153 | 400 | 272 | |
| 5 | 52 | 56 | 39 | 76 | 111 | 76 | 105 | 185 | 122 | 148 | 277 | 186 | 190 | 388 | 261 | |
| 10 | NA | NA | 34 | 97 | 100 | 68 | 132 | 171 | 112 | 188 | 261 | 171 | 237 | 369 | 241 | |
| 15 | 0 | 36 | 93 | 57 | 56 | 190 | 111 | 80 | 325 | 186 | 116 | 499 | 283 | 153 | 713 | 388 |
| 2 | 38 | 69 | 47 | 57 | 136 | 93 | 80 | 225 | 149 | 115 | 337 | 224 | 148 | 473 | 314 | |
| 5 | 51 | 63 | 44 | 75 | 128 | 86 | 102 | 216 | 140 | 144 | 326 | 217 | 182 | 459 | 298 | |
| 10 | NA | NA | 39 | 95 | 116 | 79 | 128 | 201 | 131 | 182 | 308 | 203 | 228 | 438 | 284 | |
| 15 | NA | NA | NA | NA | NA | 72 | 158 | 186 | 124 | 220 | 290 | 192 | 272 | 418 | 269 | |
| 20 | 0 | 35 | 96 | 60 | 54 | 200 | 118 | 78 | 346 | 201 | 114 | 537 | 306 | 149 | 772 | 428 |
| 2 | 37 | 74 | 50 | 56 | 148 | 99 | 78 | 248 | 165 | 113 | 375 | 248 | 144 | 528 | 344 | |
| 5 | 50 | 68 | 47 | 73 | 140 | 94 | 100 | 239 | 158 | 141 | 363 | 239 | 178 | 514 | 334 | |
| 10 | NA | NA | 41 | 93 | 129 | 86 | 125 | 223 | 146 | 177 | 344 | 224 | 222 | 491 | 316 | |
| 15 | NA | NA | NA | NA | NA | 80 | 155 | 208 | 136 | 216 | 325 | 210 | 264 | 469 | 301 | |
| 20 | NA | NA | NA | NA | NA | NA | 186 | 192 | 126 | 254 | 306 | 196 | 309 | 448 | 285 | |
| 30 | 0 | 34 | 99 | 63 | 53 | 211 | 127 | 76 | 372 | 219 | 110 | 584 | 334 | 144 | 849 | 472 |
| 2 | 37 | 80 | 56 | 55 | 164 | 111 | 76 | 281 | 183 | 109 | 429 | 279 | 139 | 610 | 392 | |
| 5 | 49 | 74 | 52 | 72 | 157 | 106 | 98 | 271 | 173 | 136 | 417 | 271 | 171 | 595 | 382 | |
| 10 | NA | NA | NA | 91 | 144 | 98 | 122 | 255 | 168 | 171 | 397 | 257 | 213 | 570 | 367 | |
| 15 | NA | NA | NA | 115 | 131 | NA | 151 | 239 | 157 | 208 | 377 | 242 | 255 | 547 | 349 | |
| 20 | NA | NA | NA | NA | NA | NA | 181 | 223 | NA | 246 | 357 | 228 | 298 | 524 | 333 | |
| 30 | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | 389 | 477 | 305 | |
| 50 | 0 | 33 | 99 | 66 | 51 | 213 | 133 | 73 | 394 | 230 | 105 | 629 | 361 | 138 | 928 | 515 |
| 2 | 36 | 84 | 61 | 53 | 181 | 121 | 73 | 318 | 205 | 104 | 495 | 312 | 133 | 712 | 443 | |
| 5 | 48 | 80 | NA | 70 | 174 | 117 | 94 | 308 | 198 | 131 | 482 | 305 | 164 | 696 | 435 | |
| 10 | NA | NA | NA | 89 | 160 | NA | 118 | 292 | 186 | 162 | 461 | 292 | 203 | 671 | 420 | |
| 15 | NA | NA | NA | 112 | 148 | NA | 145 | 275 | 174 | 199 | 441 | 280 | 244 | 646 | 405 | |
| 20 | NA | NA | NA | NA | NA | NA | 176 | 257 | NA | 236 | 420 | 267 | 285 | 622 | 389 | |
| 30 | NA | NA | NA | NA | NA | NA | NA | NA | NA | 315 | 376 | NA | 373 | 573 | NA | |
| 100 | 0 | NA | NA | NA | 49 | 214 | NA | 69 | 403 | NA | 100 | 659 | 395 | 131 | 991 | 555 |
| 2 | NA | NA | NA | 51 | 192 | NA | 70 | 351 | NA | 98 | 563 | 373 | 125 | 828 | 508 | |
| 5 | NA | NA | NA | 67 | 186 | NA | 90 | 342 | NA | 125 | 551 | 366 | 156 | 813 | 501 | |
| 10 | NA | NA | NA | 85 | 175 | NA | 113 | 324 | NA | 153 | 532 | 354 | 191 | 789 | 486 | |
| 15 | NA | NA | NA | 132 | 162 | NA | 138 | 310 | NA | 188 | 511 | 343 | 230 | 764 | 473 | |
| 20 | NA | NA | NA | NA | NA | NA | 168 | 295 | NA | 224 | 487 | NA | 270 | 739 | 458 | |
| 30 | NA | NA | NA | NA | NA | NA | 231 | 264 | NA | 301 | 448 | NA | 355 | 685 | NA | |
| 50 | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | 540 | 584 | NA | |
* NA: Not applicable.
| NUMBER OF APPLIANCES: | SINGLE | ||||||||||||
| APPLIANCE TYPE: | CATEGORY I | ||||||||||||
| APPLIANCE VENT CONNECTION: | SINGLE-WALL METAL CONNECTOR | ||||||||||||
| VENT DIAMETER - D (inch) | |||||||||||||
| 8 | 9 | 10 | 12 | ||||||||||
| APPLIANCE INPUT RATING IN THOUSANDS OF BTU PER HOUR | |||||||||||||
| HEIGHT H (feet) |
LATERAL L (feet) |
FAN | NAT | FAN | NAT | FAN | NAT | FAN | NAT | ||||
| Min | Max | Max | Min | Max | Max | Min | Max | Max | Min | Max | Max | ||
| 6 | 0 | 211 | 695 | 369 | 267 | 894 | 469 | 371 | 1118 | 569 | 537 | 1639 | 849 |
| 2 | 201 | 423 | 284 | 251 | 541 | 368 | 347 | 673 | 453 | 498 | 979 | 648 | |
| 4 | 237 | 416 | 277 | 295 | 533 | 360 | 409 | 664 | 443 | 584 | 971 | 638 | |
| 6 | 263 | 409 | 271 | 327 | 526 | 352 | 449 | 656 | 433 | 638 | 962 | 627 | |
| 8 | 0 | 206 | 777 | 141 | 258 | 1002 | 536 | 360 | 1257 | 658 | 521 | 1852 | 967 |
| 2 | 197 | 482 | 321 | 246 | 617 | 417 | 339 | 768 | 513 | 486 | 1120 | 743 | |
| 5 | 245 | 470 | 311 | 305 | 604 | 404 | 418 | 754 | 500 | 598 | 1104 | 730 | |
| 8 | 280 | 458 | 300 | 344 | 591 | 392 | 470 | 740 | 486 | 665 | 1089 | 715 | |
| 10 | 0 | 202 | 844 | 449 | 253 | 1093 | 584 | 351 | 1373 | 718 | 507 | 2031 | 1057 |
| 2 | 193 | 531 | 354 | 242 | 681 | 456 | 332 | 849 | 559 | 475 | 1242 | 848 | |
| 5 | 241 | 518 | 344 | 299 | 667 | 443 | 409 | 834 | 544 | 584 | 1224 | 825 | |
| 10 | 296 | 497 | 325 | 363 | 643 | 423 | 492 | 808 | 520 | 688 | 1194 | 788 | |
| 15 | 0 | 195 | 966 | 523 | 244 | 1259 | 681 | 336 | 1591 | 838 | 488 | 2374 | 1237 |
| 2 | 187 | 631 | 413 | 232 | 812 | 543 | 319 | 1015 | 673 | 457 | 1491 | 983 | |
| 5 | 231 | 616 | 400 | 287 | 795 | 526 | 392 | 997 | 657 | 562 | 1469 | 963 | |
| 10 | 284 | 592 | 381 | 349 | 768 | 501 | 470 | 966 | 628 | 664 | 1433 | 928 | |
| 15 | 334 | 568 | 367 | 404 | 742 | 484 | 540 | 937 | 601 | 750 | 1399 | 894 | |
| 20 | 0 | 190 | 1053 | 573 | 238 | 1379 | 750 | 326 | 1751 | 927 | 473 | 2631 | 1346 |
| 2 | 182 | 708 | 468 | 227 | 914 | 611 | 309 | 1146 | 754 | 443 | 1689 | 1098 | |
| 5 | 224 | 692 | 457 | 279 | 896 | 596 | 381 | 1126 | 734 | 547 | 1665 | 1074 | |
| 10 | 277 | 666 | 437 | 339 | 866 | 570 | 457 | 1092 | 702 | 646 | 1626 | 1037 | |
| 15 | 325 | 640 | 419 | 393 | 838 | 549 | 526 | 1060 | 677 | 730 | 1587 | 1005 | |
| 20 | 374 | 616 | 400 | 448 | 810 | 526 | 592 | 1028 | 651 | 808 | 1550 | 973 | |
| 30 | 0 | 184 | 1168 | 647 | 229 | 1542 | 852 | 312 | 1971 | 1056 | 454 | 2996 | 1545 |
| 2 | 175 | 823 | 533 | 219 | 1069 | 698 | 296 | 1346 | 863 | 424 | 1999 | 1308 | |
| 5 | 215 | 806 | 521 | 269 | 1049 | 684 | 366 | 1324 | 846 | 524 | 1971 | 1283 | |
| 10 | 265 | 777 | 501 | 327 | 1017 | 662 | 440 | 1287 | 821 | 620 | 1927 | 1243 | |
| 15 | 312 | 750 | 481 | 379 | 985 | 638 | 507 | 1251 | 794 | 702 | 1884 | 1205 | |
| 20 | 360 | 723 | 461 | 433 | 955 | 615 | 570 | 1216 | 768 | 780 | 1841 | 1166 | |
| 30 | 461 | 670 | 426 | 541 | 895 | 574 | 704 | 1147 | 720 | 937 | 1759 | 1101 | |
| 50 | 0 | 176 | 1292 | 704 | 220 | 1724 | 948 | 295 | 2223 | 1189 | 428 | 3432 | 1818 |
| 2 | 168 | 971 | 613 | 209 | 1273 | 811 | 280 | 1615 | 1007 | 401 | 2426 | 1509 | |
| 5 | 204 | 953 | 602 | 257 | 1252 | 795 | 347 | 1591 | 991 | 496 | 2396 | 1490 | |
| 10 | 253 | 923 | 583 | 313 | 1217 | 765 | 418 | 1551 | 963 | 589 | 2347 | 1455 | |
| 15 | 299 | 894 | 562 | 363 | 1183 | 736 | 481 | 1512 | 934 | 668 | 2299 | 1421 | |
| 20 | 345 | 866 | 543 | 415 | 1150 | 708 | 544 | 1473 | 906 | 741 | 2251 | 1387 | |
| 30 | 442 | 809 | 502 | 521 | 1086 | 649 | 674 | 1399 | 848 | 892 | 2159 | 1318 | |
| 100 | 0 | 166 | 1404 | 765 | 207 | 1900 | 1033 | 273 | 2479 | 1300 | 395 | 3912 | 2042 |
| 2 | 158 | 1152 | 698 | 196 | 1532 | 933 | 259 | 1970 | 1168 | 371 | 3021 | 1817 | |
| 5 | 194 | 1134 | 688 | 240 | 1511 | 921 | 322 | 1945 | 1153 | 460 | 2990 | 1796 | |
| 10 | 238 | 1104 | 672 | 293 | 1477 | 902 | 389 | 1905 | 1133 | 547 | 2938 | 1763 | |
| 15 | 281 | 1075 | 656 | 342 | 1443 | 884 | 447 | 1865 | 1110 | 618 | 2888 | 1730 | |
| 20 | 325 | 1046 | 639 | 391 | 1410 | 864 | 507 | 1825 | 1087 | 690 | 2838 | 1696 | |
| 30 | 418 | 988 | NA | 491 | 1343 | 824 | 631 | 1747 | 1041 | 834 | 2739 | 1627 | |
| 50 | 617 | 866 | NA | 711 | 1205 | NA | 895 | 1591 | NA | 1138 | 2547 | 1489 | |
* NA: Not applicable.
| NUMBER OF APPLIANCES: | SINGLE | |||||||||||||||
| APPLIANCE TYPE: | CATEGORY I | |||||||||||||||
| APPLIANCE VENT CONNECTION: | TYPE B DOUBLE-WALL CONNECTOR | |||||||||||||||
| TYPE B DOUBLE-WALL CONNECTOR DIAMETER - D (inch) TO BE USED WITH CHIMNEY AREAS WITHIN THE SIZE LIMITS AT BOTTOM |
||||||||||||||||
| 3 | 4 | 5 | 6 | 7 | ||||||||||||
| APPLIANCE INPUT RATING IN THOUSANDS OF BTU PER HOUR | ||||||||||||||||
| HEIGHT H (feet) |
LATERAL L (feet) |
FAN | NAT | FAN | NAT | FAN | NAT | FAN | NAT | FAN | NAT | |||||
| Min | Max | Max | Min | Max | Max | Min | Max | Max | Min | Max | Max | Min | Max | Max | ||
| 6 | 2 | NA | NA | 28 | NA | NA | 52 | NA | NA | 86 | NA | NA | 130 | NA | NA | 180 |
| 5 | NA | NA | 25 | NA | NA | 49 | NA | NA | 82 | NA | NA | 117 | NA | NA | 165 | |
| 8 | 2 | NA | NA | 29 | NA | NA | 55 | NA | NA | 93 | NA | NA | 145 | NA | NA | 198 |
| 5 | NA | NA | 26 | NA | NA | 52 | NA | NA | 88 | NA | NA | 134 | NA | NA | 183 | |
| 8 | NA | NA | 24 | NA | NA | 48 | NA | NA | 83 | NA | NA | 127 | NA | NA | 175 | |
| 10 | 2 | NA | NA | 31 | NA | NA | 61 | NA | NA | 103 | NA | NA | 162 | NA | NA | 221 |
| 5 | NA | NA | 28 | NA | NA | 57 | NA | NA | 96 | NA | NA | 148 | NA | NA | 204 | |
| 10 | NA | NA | 25 | NA | NA | 50 | NA | NA | 87 | NA | NA | 139 | NA | NA | 191 | |
| 15 | 2 | NA | NA | 35 | NA | NA | 67 | NA | NA | 114 | NA | NA | 179 | 53 | 475 | 250 |
| 5 | NA | NA | 35 | NA | NA | 62 | NA | NA | 107 | NA | NA | 164 | NA | NA | 231 | |
| 10 | NA | NA | 28 | NA | NA | 55 | NA | NA | 97 | NA | NA | 153 | NA | NA | 216 | |
| 15 | NA | NA | NA | NA | NA | 48 | NA | NA | 89 | NA | NA | 141 | NA | NA | 201 | |
| 20 | 2 | NA | NA | 38 | NA | NA | 74 | NA | NA | 124 | NA | NA | 201 | 51 | 522 | 274 |
| 5 | NA | NA | 36 | NA | NA | 68 | NA | NA | 116 | NA | NA | 184 | 80 | 503 | 254 | |
| 10 | NA | NA | NA | NA | NA | 60 | NA | NA | 107 | NA | NA | 172 | NA | NA | 237 | |
| 15 | NA | NA | NA | NA | NA | NA | NA | NA | 97 | NA | NA | 159 | NA | NA | 220 | |
| 20 | NA | NA | NA | NA | NA | NA | NA | NA | 83 | NA | NA | 148 | NA | NA | 206 | |
| 30 | 2 | NA | NA | 41 | NA | NA | 82 | NA | NA | 137 | NA | NA | 216 | 47 | 581 | 303 |
| 5 | NA | NA | NA | NA | NA | 76 | NA | NA | 128 | NA | NA | 198 | 75 | 561 | 281 | |
| 10 | NA | NA | NA | NA | NA | 67 | NA | NA | 115 | NA | NA | 184 | NA | NA | 263 | |
| 15 | NA | NA | NA | NA | NA | NA | NA | NA | 107 | NA | NA | 171 | NA | NA | 243 | |
| 20 | NA | NA | NA | NA | NA | NA | NA | NA | 91 | NA | NA | 159 | NA | NA | 227 | |
| 30 | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | 188 | |
| 50 | 2 | NA | NA | NA | NA | NA | 92 | NA | NA | 161 | NA | NA | 251 | NA | NA | 351 |
| 5 | NA | NA | NA | NA | NA | NA | NA | NA | 151 | NA | NA | 230 | NA | NA | 323 | |
| 10 | NA | NA | NA | NA | NA | NA | NA | NA | 138 | NA | NA | 215 | NA | NA | 304 | |
| 15 | NA | NA | NA | NA | NA | NA | NA | NA | 127 | NA | NA | 199 | NA | NA | 282 | |
| 20 | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | 185 | NA | NA | 264 | |
| 30 | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | |
| Minimum internal area of chimney (square inches) |
12 | 19 | 28 | 38 | 50 | |||||||||||
| Maximum internal area of chimney (square inches) |
Seven times the listed appliance categorized vent area, flue collar area, or draft hood outlet areas. | |||||||||||||||
* NA: Not applicable.
| NUMBER OF APPLIANCES: | SINGLE | ||||||||||||
| APPLIANCE TYPE: | CATEGORY I | ||||||||||||
| APPLIANCE VENT CONNECTION: | TYPE B DOUBLE-WALL CONNECTOR | ||||||||||||
| TYPE B DOUBLE-WALL CONNECTOR DIAMETER - D (inch) TO BE USED WITH CHIMNEY AREAS WITHIN THE SIZE LIMITS AT BOTTOM |
|||||||||||||
| 8 | 9 | 10 | 12 | ||||||||||
| APPLIANCE INPUT RATING IN THOUSANDS OF BTU PER HOUR | |||||||||||||
| HEIGHT H (feet) |
LATERAL L (feet) |
FAN | NAT | FAN | NAT | FAN | NAT | FAN | NAT | ||||
| Min | Max | Max | Min | Max | Max | Min | Max | Max | Min | Max | Max | ||
| 6 | 2 | NA | NA | 247 | NA | NA | 320 | NA | NA | 401 | NA | NA | 581 |
| 5 | NA | NA | 231 | NA | NA | 298 | NA | NA | 376 | NA | NA | 561 | |
| 8 | 2 | NA | NA | 266 | 84 | 590 | 350 | 100 | 728 | 446 | 139 | 1024 | 651 |
| 5 | NA | NA | 247 | NA | NA | 328 | 149 | 711 | 423 | 201 | 1007 | 640 | |
| 8 | NA | NA | 239 | NA | NA | 318 | 173 | 695 | 410 | 231 | 990 | 623 | |
| 10 | 2 | 68 | 519 | 298 | 82 | 655 | 388 | 98 | 810 | 491 | 136 | 1144 | 724 |
| 5 | NA | NA | 277 | 124 | 638 | 365 | 146 | 791 | 466 | 196 | 1124 | 712 | |
| 10 | NA | NA | 263 | 155 | 610 | 347 | 182 | 762 | 444 | 240 | 1093 | 668 | |
| 15 | 2 | 64 | 613 | 336 | 77 | 779 | 441 | 92 | 968 | 562 | 127 | 1376 | 841 |
| 5 | 99 | 594 | 313 | 118 | 759 | 416 | 139 | 946 | 533 | 186 | 1352 | 828 | |
| 10 | 126 | 565 | 296 | 148 | 727 | 394 | 173 | 912 | 567 | 229 | 1315 | 777 | |
| 15 | NA | NA | 281 | 171 | 698 | 375 | 198 | 880 | 485 | 259 | 1280 | 742 | |
| 20 | 2 | 61 | 678 | 375 | 73 | 867 | 491 | 87 | 1083 | 627 | 121 | 1548 | 953 |
| 5 | 95 | 658 | 350 | 113 | 845 | 463 | 133 | 1059 | 597 | 179 | 1523 | 933 | |
| 10 | 122 | 627 | 332 | 143 | 811 | 440 | 167 | 1022 | 566 | 221 | 1482 | 879 | |
| 15 | NA | NA | 314 | 165 | 780 | 418 | 191 | 987 | 541 | 251 | 1443 | 840 | |
| 20 | NA | NA | 296 | 186 | 750 | 397 | 214 | 955 | 513 | 277 | 1406 | 807 | |
| 30 | 2 | 57 | 762 | 421 | 68 | 985 | 558 | 81 | 1240 | 717 | 111 | 1793 | 1112 |
| 5 | 90 | 741 | 393 | 106 | 962 | 526 | 125 | 1216 | 683 | 169 | 1766 | 1094 | |
| 10 | 115 | 709 | 373 | 135 | 927 | 500 | 158 | 1176 | 648 | 210 | 1721 | 1025 | |
| 15 | NA | NA | 353 | 156 | 893 | 476 | 181 | 1139 | 621 | 239 | 1679 | 981 | |
| 20 | NA | NA | 332 | 176 | 860 | 450 | 203 | 1103 | 592 | 264 | 1638 | 940 | |
| 30 | NA | NA | 288 | NA | NA | 416 | 249 | 1035 | 555 | 318 | 1560 | 877 | |
| 50 | 2 | 51 | 840 | 477 | 61 | 1106 | 633 | 72 | 1413 | 812 | 99 | 2080 | 1243 |
| 5 | 83 | 819 | 445 | 98 | 1083 | 596 | 116 | 1387 | 774 | 155 | 2052 | 1225 | |
| 10 | NA | NA | 424 | 126 | 1047 | 567 | 147 | 1347 | 733 | 195 | 2006 | 1147 | |
| 15 | NA | NA | 400 | 146 | 1010 | 539 | 170 | 1307 | 702 | 222 | 1961 | 1099 | |
| 20 | NA | NA | 376 | 165 | 977 | 511 | 190 | 1269 | 669 | 246 | 1916 | 1050 | |
| 30 | NA | NA | 327 | NA | NA | 468 | 233 | 1196 | 623 | 295 | 1832 | 984 | |
| Minimum internal area of chimney (square inches) |
63 | 78 | 95 | 132 | |||||||||
| Maximum internal area of chimney (square inches) |
Seven times the listed appliance categorized vent area, flue collar area, or draft hood outlet areas. | ||||||||||||
* NA: Not applicable.
| NUMBER OF APPLIANCES: | SINGLE | |||||||||||||||
| APPLIANCE TYPE: | CATEGORY I | |||||||||||||||
| APPLIANCE VENT CONNECTION: | SINGLE-WALL METAL CONNECTOR | |||||||||||||||
| TYPE B DOUBLE-WALL CONNECTOR DIAMETER - D (inch) TO BE USED WITH CHIMNEY AREAS WITHIN THE SIZE LIMITS AT BOTTOM |
||||||||||||||||
| 3 | 4 | 5 | 6 | 7 | ||||||||||||
| APPLIANCE INPUT RATING IN THOUSANDS OF BTU PER HOUR | ||||||||||||||||
| HEIGHT H (feet) |
LATERAL L (feet) |
FAN | NAT | FAN | NAT | FAN | NAT | FAN | NAT | FAN | NAT | |||||
| Min | Max | Max | Min | Max | Max | Min | Max | Max | Min | Max | Max | Min | Max | Max | ||
| 6 | 2 | NA | NA | 28 | NA | NA | 52 | NA | NA | 86 | NA | NA | 130 | NA | NA | 180 |
| 5 | NA | NA | 25 | NA | NA | 48 | NA | NA | 81 | NA | NA | 116 | NA | NA | 164 | |
| 8 | 2 | NA | NA | 29 | NA | NA | 55 | NA | NA | 93 | NA | NA | 145 | NA | NA | 197 |
| 5 | NA | NA | 26 | NA | NA | 51 | NA | NA | 87 | NA | NA | 133 | NA | NA | 182 | |
| 8 | NA | NA | 23 | NA | NA | 47 | NA | NA | 82 | NA | NA | 126 | NA | NA | 174 | |
| 10 | 2 | NA | NA | 31 | NA | NA | 61 | NA | NA | 102 | NA | NA | 161 | NA | NA | 220 |
| 5 | NA | NA | 28 | NA | NA | 56 | NA | NA | 95 | NA | NA | 147 | NA | NA | 203 | |
| 10 | NA | NA | 24 | NA | NA | 49 | NA | NA | 86 | NA | NA | 137 | NA | NA | 189 | |
| 15 | 2 | NA | NA | 35 | NA | NA | 67 | NA | NA | 113 | NA | NA | 178 | 166 | 473 | 249 |
| 5 | NA | NA | 32 | NA | NA | 61 | NA | NA | 106 | NA | NA | 163 | NA | NA | 230 | |
| 10 | NA | NA | 27 | NA | NA | 54 | NA | NA | 96 | NA | NA | 151 | NA | NA | 214 | |
| 15 | NA | NA | NA | NA | NA | 46 | NA | NA | 87 | NA | NA | 138 | NA | NA | 198 | |
| 20 | 2 | NA | NA | 38 | NA | NA | 73 | NA | NA | 123 | NA | NA | 200 | 163 | 520 | 273 |
| 5 | NA | NA | 35 | NA | NA | 67 | NA | NA | 115 | NA | NA | 183 | NA | NA | 252 | |
| 10 | NA | NA | NA | NA | NA | 59 | NA | NA | 105 | NA | NA | 170 | NA | NA | 235 | |
| 15 | NA | NA | NA | NA | NA | NA | NA | NA | 95 | NA | NA | 156 | NA | NA | 217 | |
| 20 | NA | NA | NA | NA | NA | NA | NA | NA | 80 | NA | NA | 144 | NA | NA | 202 | |
| 30 | 2 | NA | NA | 41 | NA | NA | 81 | NA | NA | 136 | NA | NA | 215 | 158 | 578 | 302 |
| 5 | NA | NA | NA | NA | NA | 75 | NA | NA | 127 | NA | NA | 196 | NA | NA | 279 | |
| 10 | NA | NA | NA | NA | NA | 66 | NA | NA | 113 | NA | NA | 182 | NA | NA | 260 | |
| 15 | NA | NA | NA | NA | NA | NA | NA | NA | 105 | NA | NA | 168 | NA | NA | 240 | |
| 20 | NA | NA | NA | NA | NA | NA | NA | NA | 88 | NA | NA | 155 | NA | NA | 223 | |
| 30 | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | 182 | |
| 50 | 2 | NA | NA | NA | NA | NA | 91 | NA | NA | 160 | NA | NA | 250 | NA | NA | 350 |
| 5 | NA | NA | NA | NA | NA | NA | NA | NA | 149 | NA | NA | 228 | NA | NA | 321 | |
| 10 | NA | NA | NA | NA | NA | NA | NA | NA | 136 | NA | NA | 212 | NA | NA | 301 | |
| 15 | NA | NA | NA | NA | NA | NA | NA | NA | 124 | NA | NA | 195 | NA | NA | 278 | |
| 20 | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | 180 | NA | NA | 258 | |
| 30 | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | |
| Minimum internal area of chimney (square inches) |
12 | 19 | 28 | 38 | 50 | |||||||||||
| Maximum internal area of chimney (square inches) |
Seven times the listed appliance categorized vent area, flue collar area, or draft hood outlet areas. | |||||||||||||||
* NA: Not applicable.
| NUMBER OF APPLIANCES: | SINGLE | ||||||||||||
| APPLIANCE TYPE: | CATEGORY I | ||||||||||||
| APPLIANCE VENT CONNECTION: | SINGLE-WALL METAL CONNECTOR | ||||||||||||
| SINGLE-WALL METAL CONNECTOR DIAMETER - D (inch) TO BE USED WITH CHIMNEY AREAS WITHIN THE SIZE LIMITS AT BOTTOM |
|||||||||||||
| 8 | 9 | 10 | 12 | ||||||||||
| APPLIANCE INPUT RATING IN THOUSANDS OF BTU PER HOUR | |||||||||||||
| HEIGHT H (feet) |
LATERAL L (feet) |
FAN | NAT | FAN | NAT | FAN | NAT | FAN | NAT | ||||
| Min | Max | Max | Min | Max | Max | Min | Max | Max | Min | Max | Max | ||
| 6 | 2 | NA | NA | 247 | NA | NA | 319 | NA | NA | 400 | NA | NA | 580 |
| 5 | NA | NA | 230 | NA | NA | 297 | NA | NA | 375 | NA | NA | 560 | |
| 8 | 2 | NA | NA | 265 | NA | NA | 349 | 382 | 725 | 445 | 549 | 1021 | 650 |
| 5 | NA | NA | 246 | NA | NA | 327 | NA | NA | 422 | 673 | 1003 | 638 | |
| 8 | NA | NA | 237 | NA | NA | 317 | NA | NA | 408 | 747 | 985 | 621 | |
| 10 | 2 | 216 | 518 | 297 | 271 | 654 | 387 | 373 | 808 | 490 | 536 | 1142 | 722 |
| 5 | NA | NA | 276 | 334 | 635 | 364 | 459 | 789 | 465 | 657 | 1121 | 710 | |
| 10 | NA | NA | 261 | NA | NA | 345 | 547 | 758 | 441 | 771 | 1088 | 665 | |
| 15 | 2 | 211 | 611 | 335 | 264 | 776 | 440 | 362 | 965 | 560 | 520 | 1373 | 840 |
| 5 | 261 | 591 | 312 | 325 | 755 | 414 | 444 | 942 | 531 | 637 | 1348 | 825 | |
| 10 | NA | NA | 294 | 392 | 722 | 392 | 531 | 907 | 504 | 749 | 1309 | 774 | |
| 15 | NA | NA | 278 | 452 | 692 | 372 | 606 | 873 | 481 | 841 | 1272 | 738 | |
| 20 | 2 | 206 | 675 | 374 | 258 | 864 | 490 | 252 | 1079 | 625 | 508 | 1544 | 950 |
| 5 | 255 | 655 | 348 | 317 | 842 | 461 | 433 | 1055 | 594 | 623 | 1518 | 930 | |
| 10 | 312 | 622 | 330 | 382 | 806 | 437 | 517 | 1016 | 562 | 733 | 1475 | 875 | |
| 15 | NA | NA | 311 | 442 | 773 | 414 | 591 | 979 | 539 | 823 | 1434 | 835 | |
| 20 | NA | NA | 292 | NA | NA | 392 | 663 | 944 | 510 | 911 | 1394 | 800 | |
| 30 | 2 | 200 | 759 | 420 | 249 | 982 | 556 | 340 | 1237 | 715 | 489 | 1789 | 1110 |
| 5 | 245 | 737 | 391 | 306 | 958 | 524 | 417 | 1210 | 680 | 600 | 1760 | 1090 | |
| 10 | 300 | 703 | 370 | 370 | 920 | 496 | 500 | 1168 | 644 | 708 | 1713 | 1020 | |
| 15 | NA | NA | 349 | 428 | 884 | 471 | 572 | 1128 | 615 | 798 | 1668 | 975 | |
| 20 | NA | NA | 327 | NA | NA | 445 | 643 | 1089 | 585 | 883 | 1624 | 932 | |
| 30 | NA | NA | 281 | NA | NA | 408 | NA | NA | 544 | 1055 | 1539 | 865 | |
| 50 | 2 | 191 | 837 | 475 | 238 | 1103 | 631 | 323 | 1408 | 810 | 463 | 2076 | 1240 |
| 5 | NA | NA | 442 | 293 | 1078 | 593 | 398 | 1381 | 770 | 571 | 2044 | 1220 | |
| 10 | NA | NA | 420 | 355 | 1038 | 562 | 447 | 1337 | 728 | 674 | 1994 | 1140 | |
| 15 | NA | NA | 395 | NA | NA | 533 | 546 | 1294 | 695 | 761 | 1945 | 1090 | |
| 20 | NA | NA | 370 | NA | NA | 504 | 616 | 1251 | 660 | 844 | 1898 | 1040 | |
| 30 | NA | NA | 318 | NA | NA | 458 | NA | NA | 610 | 1009 | 1805 | 970 | |
| Minimum internal area of chimney (square inches) |
63 | 78 | 95 | 132 | |||||||||
| Maximum internal area of chimney (square inches) |
Seven times the listed appliance categorized vent area, flue collar area, or draft hood outlet areas. | ||||||||||||
* NA: Not applicable.
| NUMBER OF APPLIANCES: | SINGLE | ||||||||
| APPLIANCE TYPE: | DRAFT HOOD-EQUIPPED | ||||||||
| APPLIANCE VENT CONNECTION: | CONNECTED DIRECTLY TO PIPE OR VENT | ||||||||
| DIAMETER - D (inch) TO BE USED WITH CHIMNEY AREAS WITHIN THE SIZE LIMITS AT BOTTOM |
|||||||||
| 3 | 4 | 5 | 6 | 7 | 8 | 10 | 12 | ||
| HEIGHT H (feet) |
LATERAL L (feet) |
APPLIANCE INPUT RATING IN THOUSANDS OF BTU PER HOUR | |||||||
| MAXIMUM APPLIANCE INPUT RATING IN THOUSANDS OF BTU PER HOUR | |||||||||
| 6 | 0 | 39 | 70 | 116 | 170 | 232 | 312 | 500 | 750 |
| 2 | 31 | 55 | 94 | 141 | 194 | 260 | 415 | 620 | |
| 5 | 28 | 51 | 88 | 128 | 177 | 242 | 390 | 600 | |
| 8 | 0 | 42 | 76 | 126 | 185 | 252 | 340 | 542 | 815 |
| 2 | 32 | 61 | 102 | 154 | 210 | 284 | 451 | 680 | |
| 5 | 29 | 56 | 95 | 141 | 194 | 264 | 430 | 648 | |
| 10 | 24 | 49 | 86 | 131 | 180 | 250 | 406 | 625 | |
| 10 | 0 | 45 | 84 | 138 | 202 | 279 | 372 | 606 | 912 |
| 2 | 35 | 67 | 111 | 168 | 233 | 311 | 505 | 760 | |
| 5 | 32 | 61 | 104 | 153 | 215 | 289 | 480 | 724 | |
| 10 | 27 | 54 | 94 | 143 | 200 | 274 | 455 | 700 | |
| 15 | NA | 46 | 84 | 130 | 186 | 258 | 432 | 666 | |
| 15 | 0 | 49 | 91 | 151 | 223 | 312 | 420 | 684 | 1040 |
| 2 | 39 | 72 | 122 | 186 | 260 | 350 | 570 | 865 | |
| 5 | 35 | 67 | 110 | 170 | 240 | 325 | 540 | 825 | |
| 10 | 30 | 58 | 103 | 158 | 223 | 308 | 514 | 795 | |
| 15 | NA | 50 | 93 | 144 | 207 | 291 | 488 | 760 | |
| 20 | NA | NA | 82 | 132 | 195 | 273 | 466 | 726 | |
| 20 | 0 | 53 | 101 | 163 | 252 | 342 | 470 | 770 | 1190 |
| 2 | 42 | 80 | 136 | 210 | 286 | 392 | 641 | 990 | |
| 5 | 38 | 74 | 123 | 192 | 264 | 364 | 610 | 945 | |
| 10 | 32 | 65 | 115 | 178 | 246 | 345 | 571 | 910 | |
| 15 | NA | 55 | 104 | 163 | 228 | 326 | 550 | 870 | |
| 20 | NA | NA | 91 | 149 | 214 | 306 | 525 | 832 | |
| 30 | 0 | 56 | 108 | 183 | 276 | 384 | 529 | 878 | 1370 |
| 2 | 44 | 84 | 148 | 230 | 320 | 441 | 730 | 1140 | |
| 5 | NA | 78 | 137 | 210 | 296 | 410 | 694 | 1080 | |
| 10 | NA | 68 | 125 | 196 | 274 | 388 | 656 | 1050 | |
| 15 | NA | NA | 113 | 177 | 258 | 366 | 625 | 1000 | |
| 20 | NA | NA | 99 | 163 | 240 | 344 | 596 | 960 | |
| 30 | NA | NA | NA | NA | 192 | 295 | 540 | 890 | |
| 50 | 0 | NA | 120 | 210 | 310 | 443 | 590 | 980 | 1550 |
| 2 | NA | 95 | 171 | 260 | 370 | 492 | 820 | 1290 | |
| 5 | NA | NA | 159 | 234 | 342 | 474 | 780 | 1230 | |
| 10 | NA | NA | 146 | 221 | 318 | 456 | 730 | 1190 | |
| 15 | NA | NA | NA | 200 | 292 | 407 | 705 | 1130 | |
| 20 | NA | NA | NA | 185 | 276 | 384 | 670 | 1080 | |
| 30 | NA | NA | NA | NA | 222 | 330 | 605 | 1010 | |
* NA: Not applicable.
| NUMBER OF APPLIANCES: | SINGLE | |||||||
| APPLIANCE TYPE: | NAT | |||||||
| APPLIANCE VENT CONNECTION: | TYPE B DOUBLE-WALL CONNECTOR | |||||||
| MINIMUM ALLOWABLE INPUT RATING OF SPACE-HEATING APPLIANCE IN THOUSANDS OF BTU PER HOUR | ||||||||
| VENT HEIGHT H (feet) |
INTERNAL AREA OF CHIMNEY (square inches) | |||||||
| 12 | 19 | 28 | 38 | 50 | 63 | 78 | 113 | |
| Local 99% winter design temperature: 37°F or greater | ||||||||
| 6 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 |
| 8 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 |
| 10 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 |
| 15 | NA | 0 | 0 | 0 | 0 | 0 | 0 | 0 |
| 20 | NA | NA | 123 | 190 | 249 | 184 | 0 | 0 |
| 30 | NA | NA | NA | NA | NA | 393 | 334 | 0 |
| 50 | NA | NA | NA | NA | NA | NA | NA | 579 |
| Local 99% winter design temperature: 27°F to 36°F | ||||||||
| 6 | 0 | 0 | 68 | 116 | 156 | 180 | 212 | 266 |
| 8 | 0 | 0 | 82 | 127 | 167 | 187 | 214 | 263 |
| 10 | 0 | 51 | 97 | 141 | 183 | 201 | 225 | 265 |
| 15 | NA | NA | NA | NA | 233 | 253 | 274 | 305 |
| 20 | NA | NA | NA | NA | NA | 307 | 330 | 362 |
| 30 | NA | NA | NA | NA | NA | 419 | 445 | 485 |
| 50 | NA | NA | NA | NA | NA | NA | NA | 763 |
| Local 99% winter design temperature: 17°F to 26°F | ||||||||
| 6 | NA | NA | NA | NA | NA | 215 | 259 | 349 |
| 8 | NA | NA | NA | NA | 197 | 226 | 264 | 352 |
| 10 | NA | NA | NA | NA | 214 | 245 | 278 | 358 |
| 15 | NA | NA | NA | NA | NA | 296 | 331 | 398 |
| 20 | NA | NA | NA | NA | NA | 352 | 387 | 457 |
| 30 | NA | NA | NA | NA | NA | NA | 507 | 581 |
| 50 | NA | NA | NA | NA | NA | NA | NA | NA |
| Local 99% winter design temperature: 5°F to 16°F | ||||||||
| 6 | NA | NA | NA | NA | NA | NA | NA | 416 |
| 8 | NA | NA | NA | NA | NA | NA | 312 | 423 |
| 10 | NA | NA | NA | NA | NA | 289 | 331 | 430 |
| 15 | NA | NA | NA | NA | NA | NA | 393 | 485 |
| 20 | NA | NA | NA | NA | NA | NA | 450 | 547 |
| 30 | NA | NA | NA | NA | NA | NA | NA | 682 |
| 50 | NA | NA | NA | NA | NA | NA | NA | 972 |
| Local 99% winter design temperature: -10°F to 4°F | ||||||||
| 6 | NA | NA | NA | NA | NA | NA | NA | 484 |
| 8 | NA | NA | NA | NA | NA | NA | NA | 494 |
| 10 | NA | NA | NA | NA | NA | NA | NA | 513 |
| 15 | NA | NA | NA | NA | NA | NA | NA | 586 |
| 20 | NA | NA | NA | NA | NA | NA | NA | 650 |
| 30 | NA | NA | NA | NA | NA | NA | NA | 805 |
| 50 | NA | NA | NA | NA | NA | NA | NA | 1003 |
| Local 99% winter design temperature: -11°F or lower Not recommended for any vent configurations |
||||||||
°C = (°F-32)/1.8
Notes:
- 1 See Figure 803.1.2(6) for a map showing local 99 percent winter design temperatures in the United States.
- 2 NA: Not applicable.
Zero lateral (L) shall apply to a
straight vertical vent attached to a top outlet draft hood or
flue collar. [NFPA 54:13.1.4]
Sea level input
ratings shall be used where determining maximum
capacity for high-altitude installation. Actual input (derated
for altitude) shall be used for determining minimum
capacity for high-altitude installation. [NFPA 54:13.1.5]
For appliances with
more than one input rate, the minimum vent capacity
(FAN Min) determined from the tables shall be less than
the lowest appliance input rating, and the maximum vent
capacity (FAN Max/NAT Max) determined from the
tables shall exceed the highest appliance rating input.
[NFPA 54:13.1.6]
Listed corrugated metallic chimney liner systems in
masonry chimneys shall be sized by using Table
803.1.2(1) or Table 803.1.2(2) for Type B vents, with the
maximum capacity reduced by 20 percent (0.80 x maximum
capacity) and the minimum capacity as shown in
Table 803.1.2(1) or Table 803.1.2(2).
Corrugated metallic liner systems installed with bends or offsets shall have their maximum capacity further reduced in accordance with Section 803.1.2. The 20 percent reduction for corrugated metallic chimney liner systems includes an allowance for one long radius 90 degree (1.57 rad) turn at the bottom of the liner. [NFPA 54:13.1.7]
Corrugated metallic liner systems installed with bends or offsets shall have their maximum capacity further reduced in accordance with Section 803.1.2. The 20 percent reduction for corrugated metallic chimney liner systems includes an allowance for one long radius 90 degree (1.57 rad) turn at the bottom of the liner. [NFPA 54:13.1.7]
Connections
between chimney liners and listed
double-wall connectors shall be made with listed adapters designed for
such purpose. [NFPA 54:13.1.8]
Where the vertical vent has a larger diameter than the
vent connector, the vertical vent diameter shall be used to
determine the minimum vent capacity, and the connector
diameter shall be used to determine the maximum vent
capacity. The flow area of the vertical vent shall not
exceed seven times the flow area of the listed appliance
categorized vent area, flue collar area, or draft hood outlet
area unless designed in accordance with approved
engineering methods. [NFPA 54:13.1.9]
Draft hood conversion accessories for use with masonry
chimneys venting listed Category I fan-assisted appliances
shall be listed and installed in accordance with the
listed accessory manufacturer's installation instructions.
[NFPA 54:13.1.10]
Table
803.1.2(1) through Table 803.1.2(5) shall be used only for chimneys and vents not exposed to the outdoors
below the roof line. A Type B vent or listed chimney lining
system passing through an unused masonry chimney
flue shall not be considered to be exposed to the outdoors.
Where vents extend outdoors above the roof more
than 5 feet (1524 mm) higher than required by Table
802.6.1, and where vents terminate in accordance with
Section 802.6.1(2), the outdoor portion of the vent shall
be enclosed as required by this paragraph for vents not considered to be exposed to the outdoors, or such venting
system shall be engineered. A Type B vent passing
through an unventilated enclosure or chase insulated to a
value of not less than R8 shall not be considered to be
exposed to the outdoors. Table 803.1.2(3) in combination
with Table 803.1.2(6) shall be used for clay tile-lined
exterior masonry chimneys, provided all of the following requirements are met:
- The vent connector is Type B double wall.
- The vent connector length is limited to 18 in./in. (18 mm/mm) of vent connector diameter.
- The appliance is draft hood equipped.
- The input rating is less than the maximum capacity given in Table 803.1.2(3).
- For a water heater, the outdoor design temperature shall be not less than 5°F (-15°C).
- For a space-heating appliance, the input rating is greater than the minimum capacity given by Table 803.1.2(6). [NFPA 54:13.1.11]
Flue lining system for residential and low heat appliance
shall be in accordance with
Section 803.1.11.1 and Section
803.1.11.2.
Clay flue lining
shall be manufactured in accordance with ASTM
C315 or other approved standard.
Chimney lining shall
be listed in accordance with UL 1777.
Corrugated
vent connectors shall not be smaller than the listed
appliance categorized vent diameter, flue collar diameter,
or draft hood outlet diameter.
[NFPA 54:13.1.12]
Vent connectors shall not be
upsized more than two sizes exceeding the listed appliance
categorized vent diameter, flue collar diameter, or
draft hood outlet diameter.
[NFPA 54:13.1.13]
In a single run of vent
or vent connector, more than one diameter and type shall
be permitted to be used, provided that the sizes and types
are permitted by the tables.
[NFPA 54:13.1.14]
Interpolation shall be permitted
in calculating capacities for vent dimensions that fall
between table entries. [NFPA 54:13.1.15]
Extrapolation beyond the
table entries shall not be permitted. [NFPA 54:13.1.16]
For vent heights
lower than 6 feet (1829 mm) and higher than shown in
the tables, engineering methods shall be used to calculate
vent capacities. [NFPA 54:13.1.17]
Where the actual height of a
vent falls between entries in the height column of the
applicable table in Table 803.1.2(1) through Table 803.1.2(6), either of the following shall be used:
- Interpolation.
- The lower appliance input rating shown in the table entries for FAN MAX and NAT MAX column values, and the higher appliance input rating for the FAN MIN column values. [NFPA 54:13.1.18]
Venting Table 803.2(1) through Table
803.2(9) shall not be used where obstructions are installed in
the venting system. The installation of vents serving listed
appliances with vent dampers shall be in accordance with the appliance manufacturer's instructions or in accordance with
the following:
- The maximum capacity of the vent connector shall be determined using the NAT Max column.
- The maximum capacity of the vertical vent or chimney shall be determined using the FAN+ NAT column when the second appliance is a fan-assisted appliance, or the NAT + NAT column when the second appliance is equipped with a draft hood.
-
The minimum capacity shall be determined as if the
appliance were a fan-assisted appliance, as follows:
- The minimum capacity of the vent connector shall be determined using the FAN Min column.
- The FAN+ FAN column shall be used when the second appliance is a fan-assisted appliance, and the FAN+ NAT column shall be used when the second appliance is equipped with a draft hood, to determine whether the vertical vent or chimney configuration is not permitted (NA). Where the vent configuration is NA, the vent configuration shall not be permitted and an alternative venting configuration shall be utilized. [NFPA 54:13.2.1]
Venting Table 803.2(1) through Table
803.2(9) shall not be used where obstructions are installed in
the venting system. The installation of vents serving listed
appliances with vent dampers shall be in accordance with the appliance manufacturer's instructions or in accordance with
the following:
For SI units: 1 inch = 25.4 mm, 1 foot = 304.8 mm, 1000 British thermal units per hour = 0.293 kW, 1 square inch = 0.000645 m2
* NA: Not applicable.
For SI units: 1 inch = 25.4 mm, 1 foot = 304.8 mm, 1000 British thermal units per hour = 0.293 kW, 1 square inch = 0.000645 m2
For SI units: 1 inch = 25.4 mm, 1 foot = 304.8 mm, 1000 British thermal units per hour = 0.293 kW, 1 square inch = 0.000645 m2
* NA: Not applicable.
For SI units: 1 inch = 25.4 mm, 1 foot = 304.8 mm, 1000 British thermal units per hour = 0.293 kW, 1 square inch = 0.000645 m2
* NA: Not applicable.
For SI units: 1 inch = 25.4 mm, 1 foot = 304.8 mm, 1000 British thermal units per hour = 0.293 kW, 1 square inch = 0.000645 m2
* NA: Not applicable.
For SI units: 1 inch = 25.4 mm, 1 foot = 304.8 mm, 1000 British thermal units per hour = 0.293 kW, 1 square inch = 0.000645 m2
For SI units: 1 inch = 25.4 mm, 1 foot = 304.8 mm, 1000 British thermal units per hour = 0.293 kW, 1 square inch = 0.000645 m2
* NA: Not applicable.
For SI units: 1 inch = 25.4 mm, 1 foot = 304.8 mm, 1000 British thermal units per hour = 0.293 kW, 1 square inch = 0.000645 m2
* NA: Not applicable.
For SI units: 1 inch = 25.4 mm, 1 foot = 304.8 mm, 1000 British thermal units per hour = 0.293 kW, 1 square inch = 0.000645 m2
* NA: Not applicable.
For SI units: 1 inch = 25.4 mm, 1 foot = 304.8 mm, 1000 British thermal units per hour = 0.293 kW, 1 square inch = 0.000645 m2
* NA: Not applicable.
For SI units: 1 inch = 25.4 mm, 1 foot = 304.8 mm, 1000 British thermal units per hour = 0.293 kW, 1 square inch = 0.000645 m2
* NA: Not applicable.
For SI units: 1 inch = 25.4 mm, 1 foot = 304.8 mm, 1000 British thermal units per hour = 0.293 kW, 1 square inch = 0.000645 m2
* NA: Not applicable.
For SI units: 1 inch = 25.4 mm, 1 foot = 304.8 mm, 1000 British thermal units per hour = 0.293 kW, 1 square inch = 0.000645 m2, °C = (°F-32)/1.8
Notes:
For SI units: 1 inch = 25.4 mm, 1 foot = 304.8 mm, 1000 British thermal units per hour = 0.293 kW, 1 square inch = 0.000645 m2
* NA: Not applicable.
For SI units: 1 inch = 25.4 mm, 1 foot = 304.8 mm, 1000 British thermal units per hour = 0.293 kW, 1 square inch = 0.000645 m2, °C = (°F-32)/1.8
Notes:
- The maximum capacity of the vent connector shall be determined using the NAT Max column.
- The maximum capacity of the vertical vent or chimney shall be determined using the FAN+ NAT column when the second appliance is a fan-assisted appliance, or the NAT + NAT column when the second appliance is equipped with a draft hood.
-
The minimum capacity shall be determined as if the
appliance were a fan-assisted appliance, as follows:
- The minimum capacity of the vent connector shall be determined using the FAN Min column.
- The FAN+ FAN column shall be used when the second appliance is a fan-assisted appliance, and the FAN+ NAT column shall be used when the second appliance is equipped with a draft hood, to determine whether the vertical vent or chimney configuration is not permitted (NA). Where the vent configuration is NA, the vent configuration shall not be permitted and an alternative venting configuration shall be utilized. [NFPA 54:13.2.1]
| NUMBER OF APPLIANCES: | TWO OR MORE | |||||||||||||||
| APPLIANCE TYPE: | CATEGORY I | |||||||||||||||
| APPLIANCE VENT CONNECTION: | TYPE B DOUBLE-WALL CONNECTOR | |||||||||||||||
| VENT CONNECTOR CAPACITY | ||||||||||||||||
| TYPE B DOUBLE-WALL VENT AND CONNECTOR DIAMETER - D (inch) | ||||||||||||||||
| 3 | 4 | 5 | 6 | 7 | ||||||||||||
| APPLIANCE INPUT RATING LIMITS IN THOUSANDS OF BTU PER HOUR | ||||||||||||||||
| VENT HEIGHT H (feet) |
CONNECTOR RISE R (feet) |
FAN | NAT | FAN | NAT | FAN | NAT | FAN | NAT | FAN | NAT | |||||
| Min | Max | Max | Min | Max | Max | Min | Max | Max | Min | Max | Max | Min | Max | Max | ||
| 6 | 1 | 22 | 37 | 26 | 35 | 66 | 46 | 46 | 106 | 72 | 58 | 164 | 104 | 77 | 225 | 142 |
| 2 | 23 | 41 | 31 | 37 | 75 | 55 | 48 | 121 | 86 | 60 | 183 | 124 | 79 | 253 | 168 | |
| 3 | 24 | 44 | 35 | 38 | 81 | 62 | 49 | 132 | 96 | 62 | 199 | 139 | 82 | 275 | 189 | |
| 8 | 1 | 22 | 40 | 27 | 35 | 72 | 48 | 49 | 114 | 76 | 64 | 176 | 109 | 84 | 243 | 148 |
| 2 | 23 | 44 | 32 | 36 | 80 | 57 | 51 | 128 | 90 | 66 | 195 | 129 | 86 | 269 | 175 | |
| 3 | 24 | 47 | 36 | 37 | 87 | 64 | 53 | 139 | 101 | 67 | 210 | 145 | 88 | 290 | 198 | |
| 10 | 1 | 22 | 43 | 28 | 34 | 78 | 50 | 49 | 123 | 78 | 65 | 189 | 113 | 89 | 257 | 154 |
| 2 | 23 | 47 | 33 | 36 | 86 | 59 | 51 | 136 | 93 | 67 | 206 | 134 | 91 | 282 | 182 | |
| 3 | 24 | 50 | 37 | 37 | 92 | 67 | 52 | 146 | 104 | 69 | 220 | 150 | 94 | 303 | 205 | |
| 15 | 1 | 21 | 50 | 30 | 33 | 89 | 53 | 47 | 142 | 83 | 64 | 220 | 120 | 88 | 298 | 163 |
| 2 | 22 | 53 | 35 | 35 | 96 | 63 | 49 | 153 | 99 | 66 | 235 | 142 | 91 | 320 | 193 | |
| 3 | 24 | 55 | 40 | 36 | 102 | 71 | 51 | 163 | 111 | 68 | 248 | 160 | 93 | 339 | 218 | |
| 20 | 1 | 21 | 54 | 31 | 33 | 99 | 56 | 46 | 157 | 87 | 62 | 246 | 125 | 86 | 334 | 171 |
| 2 | 22 | 57 | 37 | 34 | 105 | 66 | 48 | 167 | 104 | 64 | 259 | 149 | 89 | 354 | 202 | |
| 3 | 23 | 60 | 42 | 35 | 110 | 74 | 50 | 176 | 116 | 66 | 271 | 168 | 91 | 371 | 228 | |
| 30 | 1 | 20 | 62 | 33 | 31 | 113 | 59 | 45 | 181 | 93 | 60 | 288 | 134 | 83 | 391 | 182 |
| 2 | 21 | 64 | 39 | 33 | 118 | 70 | 47 | 190 | 110 | 62 | 299 | 158 | 85 | 408 | 215 | |
| 3 | 22 | 66 | 44 | 34 | 123 | 79 | 48 | 198 | 124 | 64 | 309 | 178 | 88 | 423 | 242 | |
| 50 | 1 | 19 | 71 | 36 | 30 | 133 | 64 | 43 | 216 | 101 | 57 | 349 | 145 | 78 | 477 | 197 |
| 2 | 21 | 73 | 43 | 32 | 137 | 76 | 45 | 223 | 119 | 59 | 358 | 172 | 81 | 490 | 234 | |
| 3 | 22 | 75 | 48 | 33 | 141 | 86 | 46 | 229 | 134 | 61 | 366 | 194 | 83 | 502 | 263 | |
| 100 | 1 | 18 | 82 | 37 | 28 | 158 | 66 | 40 | 262 | 104 | 53 | 442 | 150 | 73 | 611 | 204 |
| 2 | 19 | 83 | 44 | 30 | 161 | 79 | 42 | 267 | 123 | 55 | 447 | 178 | 75 | 619 | 242 | |
| 3 | 20 | 84 | 50 | 31 | 163 | 89 | 44 | 272 | 138 | 57 | 452 | 200 | 78 | 627 | 272 | |
| COMMON VENT CAPACITY | ||||||||||||
| TYPE B DOUBLE-WALL COMMON VENT DIAMETER - D (inch) | ||||||||||||
| 4 | 5 | 6 | 7 | |||||||||
| COMBINED APPLIANCE INPUT RATING IN THOUSANDS OF BTU PER HOUR | ||||||||||||
| VENT HEIGHT H (feet) |
FAN +FAN |
FAN +NAT |
NAT +NAT |
FAN +FAN |
FAN +NAT |
NAT +NAT |
FAN +FAN |
FAN +NAT |
NAT +NAT |
FAN +FAN |
FAN +NAT |
NAT +NAT |
| 6 | 92 | 81 | 65 | 140 | 116 | 103 | 204 | 161 | 147 | 309 | 248 | 200 |
| 8 | 101 | 90 | 73 | 155 | 129 | 114 | 224 | 178 | 163 | 339 | 275 | 223 |
| 10 | 110 | 97 | 79 | 169 | 141 | 124 | 243 | 194 | 178 | 367 | 299 | 242 |
| 15 | 125 | 112 | 91 | 195 | 164 | 144 | 283 | 228 | 206 | 427 | 352 | 280 |
| 20 | 136 | 123 | 102 | 215 | 183 | 160 | 314 | 255 | 229 | 475 | 394 | 310 |
| 30 | 152 | 138 | 118 | 244 | 210 | 185 | 361 | 297 | 266 | 547 | 459 | 360 |
| 50 | 167 | 153 | 134 | 279 | 244 | 214 | 421 | 353 | 310 | 641 | 547 | 423 |
| 100 | 175 | 163 | NA | 311 | 277 | NA | 489 | 421 | NA | 751 | 658 | 479 |
* NA: Not applicable.
| NUMBER OF APPLIANCES: | TWO OR MORE | |||||||||
| APPLIANCE TYPE: | CATEGORY I | |||||||||
| APPLIANCE VENT CONNECTION: | TYPE B DOUBLE-WALL CONNECTOR | |||||||||
| VENT CONNECTOR CAPACITY | ||||||||||
| TYPE B DOUBLE-WALL VENT AND CONNECTOR DIAMETER - D (inch) | ||||||||||
| 8 | 9 | 10 | ||||||||
| APPLIANCE INPUT RATING LIMITS IN THOUSANDS OF BTU PER HOUR | ||||||||||
| VENT HEIGHT H (feet) |
CONNECTOR RISE R (feet) |
FAN | NAT | FAN | NAT | FAN | NAT | |||
| Min | Max | Max | Min | Max | Max | Min | Max | Max | ||
| 6 | 1 | 92 | 296 | 185 | 109 | 376 | 237 | 128 | 466 | 289 |
| 2 | 95 | 333 | 220 | 112 | 424 | 282 | 131 | 526 | 345 | |
| 3 | 97 | 363 | 248 | 114 | 463 | 317 | 134 | 575 | 386 | |
| 8 | 1 | 100 | 320 | 194 | 118 | 408 | 248 | 138 | 507 | 303 |
| 2 | 103 | 356 | 230 | 121 | 454 | 294 | 141 | 564 | 358 | |
| 3 | 105 | 384 | 258 | 123 | 492 | 330 | 143 | 612 | 402 | |
| 10 | 1 | 106 | 341 | 200 | 125 | 436 | 257 | 146 | 542 | 314 |
| 2 | 109 | 374 | 238 | 128 | 479 | 305 | 149 | 596 | 372 | |
| 3 | 111 | 402 | 268 | 131 | 515 | 342 | 152 | 642 | 417 | |
| 15 | 1 | 110 | 389 | 214 | 134 | 493 | 273 | 162 | 609 | 333 |
| 2 | 112 | 419 | 253 | 137 | 532 | 323 | 165 | 658 | 394 | |
| 3 | 115 | 445 | 286 | 140 | 565 | 365 | 167 | 700 | 444 | |
| 20 | 1 | 107 | 436 | 224 | 131 | 552 | 285 | 158 | 681 | 347 |
| 2 | 110 | 463 | 265 | 134 | 587 | 339 | 161 | 725 | 414 | |
| 3 | 113 | 486 | 300 | 137 | 618 | 383 | 164 | 764 | 466 | |
| 30 | 1 | 103 | 512 | 238 | 125 | 649 | 305 | 151 | 802 | 372 |
| 2 | 105 | 535 | 282 | 129 | 679 | 360 | 155 | 840 | 439 | |
| 3 | 108 | 555 | 317 | 132 | 706 | 405 | 158 | 874 | 494 | |
| 50 | 1 | 97 | 627 | 257 | 120 | 797 | 330 | 144 | 984 | 403 |
| 2 | 100 | 645 | 306 | 123 | 820 | 392 | 148 | 1014 | 478 | |
| 3 | 103 | 661 | 343 | 126 | 842 | 441 | 151 | 1043 | 538 | |
| 100 | 1 | 91 | 810 | 266 | 112 | 1038 | 341 | 135 | 1285 | 417 |
| 2 | 94 | 822 | 316 | 115 | 1054 | 405 | 139 | 1306 | 494 | |
| 3 | 97 | 834 | 355 | 118 | 1069 | 455 | 142 | 1327 | 555 | |
| COMMON VENT CAPACITY | |||||||||
| TYPE B DOUBLE-WALL COMMON VENT DIAMETER - D (inch) | |||||||||
| 8 | 9 | 10 | |||||||
| COMBINED APPLIANCE INPUT RATING IN THOUSANDS OF BTU PER HOUR | |||||||||
| VENT HEIGHT H (feet) |
FAN +FAN |
FAN +NAT |
NAT +NAT |
FAN +FAN |
FAN +NAT |
NAT +NAT |
FAN +FAN |
FAN +NAT |
NAT +NAT |
| 6 | 404 | 314 | 260 | 547 | 434 | 335 | 672 | 520 | 410 |
| 8 | 444 | 348 | 290 | 602 | 480 | 378 | 740 | 577 | 465 |
| 10 | 477 | 377 | 315 | 649 | 522 | 405 | 800 | 627 | 495 |
| 15 | 556 | 444 | 365 | 753 | 612 | 465 | 924 | 733 | 565 |
| 20 | 621 | 499 | 405 | 842 | 688 | 523 | 1035 | 826 | 640 |
| 30 | 720 | 585 | 470 | 979 | 808 | 605 | 1209 | 975 | 740 |
| 50 | 854 | 706 | 550 | 1164 | 977 | 705 | 1451 | 1188 | 860 |
| 100 | 1025 | 873 | 625 | 1408 | 1215 | 800 | 1784 | 1502 | 975 |
| NUMBER OF APPLIANCES: | TWO OR MORE | ||||||||||||
| APPLIANCE TYPE: | CATEGORY I | ||||||||||||
| APPLIANCE VENT CONNECTION: | TYPE B DOUBLE-WALL CONNECTOR | ||||||||||||
| VENT CONNECTOR CAPACITY | |||||||||||||
| TYPE B DOUBLE-WALL VENT AND CONNECTOR DIAMETER - D (inch) | |||||||||||||
| 12 | 14 | 16 | 18 | ||||||||||
| APPLIANCE INPUT RATING LIMITS IN THOUSANDS OF BTU PER HOUR | |||||||||||||
| VENT HEIGHT H (feet) |
CONNECTOR RISE R (feet) |
FAN | NAT | FAN | NAT | FAN | NAT | FAN | NAT | ||||
| Min | Max | Max | Min | Max | Max | Min | Max | Max | Min | Max | Max | ||
| 6 | 2 | 174 | 764 | 496 | 223 | 1046 | 653 | 281 | 1371 | 853 | 346 | 1772 | 1080 |
| 4 | 180 | 897 | 616 | 230 | 1231 | 827 | 287 | 1617 | 1081 | 352 | 2069 | 1370 | |
| 6 | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | |
| 8 | 2 | 186 | 822 | 516 | 238 | 1126 | 696 | 298 | 1478 | 910 | 365 | 1920 | 1150 |
| 4 | 192 | 952 | 644 | 244 | 1307 | 884 | 305 | 1719 | 1150 | 372 | 2211 | 1460 | |
| 6 | 198 | 1050 | 772 | 252 | 1445 | 1072 | 313 | 1902 | 1390 | 380 | 2434 | 1770 | |
| 10 | 2 | 196 | 870 | 536 | 249 | 1195 | 730 | 311 | 1570 | 955 | 379 | 2049 | 1205 |
| 4 | 201 | 997 | 664 | 256 | 1371 | 924 | 318 | 1804 | 1205 | 387 | 2332 | 1535 | |
| 6 | 207 | 1095 | 792 | 263 | 1509 | 1118 | 325 | 1989 | 1455 | 395 | 2556 | 1865 | |
| 15 | 2 | 214 | 967 | 568 | 272 | 1334 | 790 | 336 | 1760 | 1030 | 408 | 2317 | 1305 |
| 4 | 221 | 1085 | 712 | 279 | 1499 | 1006 | 344 | 1978 | 1320 | 416 | 2579 | 1665 | |
| 6 | 228 | 1181 | 856 | 286 | 1632 | 1222 | 351 | 2157 | 1610 | 424 | 2796 | 2025 | |
| 20 | 2 | 223 | 1051 | 596 | 291 | 1443 | 840 | 357 | 1911 | 1095 | 430 | 2533 | 1385 |
| 4 | 230 | 1162 | 748 | 298 | 1597 | 1064 | 365 | 2116 | 1395 | 438 | 2778 | 1765 | |
| 6 | 237 | 1253 | 900 | 307 | 1726 | 1288 | 373 | 2287 | 1695 | 450 | 2984 | 2145 | |
| 30 | 2 | 216 | 1217 | 632 | 286 | 1664 | 910 | 367 | 2183 | 1190 | 461 | 2891 | 1540 |
| 4 | 223 | 1316 | 792 | 294 | 1802 | 1160 | 376 | 2366 | 1510 | 474 | 3110 | 1920 | |
| 6 | 231 | 1400 | 952 | 303 | 1920 | 1410 | 384 | 2524 | 1830 | 485 | 3299 | 2340 | |
| 50 | 2 | 206 | 1479 | 689 | 273 | 2023 | 1007 | 350 | 2659 | 1315 | 435 | 3548 | 1665 |
| 4 | 213 | 1561 | 860 | 281 | 2139 | 1291 | 359 | 2814 | 1685 | 447 | 3730 | 2135 | |
| 6 | 221 | 1631 | 1031 | 290 | 2242 | 1575 | 369 | 2951 | 2055 | 461 | 3893 | 2605 | |
| 100 | 2 | 192 | 1923 | 712 | 254 | 2644 | 1050 | 326 | 3490 | 1370 | 402 | 4707 | 1740 |
| 4 | 200 | 1984 | 888 | 263 | 2731 | 1346 | 336 | 3606 | 1760 | 414 | 4842 | 2220 | |
| 6 | 208 | 2035 | 1064 | 272 | 2811 | 1642 | 346 | 3714 | 2150 | 426 | 4968 | 2700 | |
| COMMON VENT CAPACITY | ||||||||||||
| TYPE B DOUBLE-WALL COMMON VENT DIAMETER - D (inch) | ||||||||||||
| 12 | 14 | 16 | 18 | |||||||||
| COMBINED APPLIANCE INPUT RATING IN THOUSANDS OF BTU PER HOUR | ||||||||||||
| VENT HEIGHT H (feet) |
FAN +FAN |
FAN +NAT |
NAT +NAT |
FAN +FAN |
FAN +NAT |
NAT +NAT |
FAN +FAN |
FAN +NAT |
NAT +NAT |
FAN +FAN |
FAN +NAT |
NAT +NAT |
| 6 | 900 | 696 | 588 | 1284 | 990 | 815 | 1735 | 1336 | 1065 | 2253 | 1732 | 1345 |
| 8 | 994 | 773 | 652 | 1423 | 1103 | 912 | 1927 | 1491 | 1190 | 2507 | 1936 | 1510 |
| 10 | 1076 | 841 | 712 | 1542 | 1200 | 995 | 2093 | 1625 | 1300 | 2727 | 2113 | 1645 |
| 15 | 1247 | 986 | 825 | 1794 | 1410 | 1158 | 2440 | 1910 | 1510 | 3184 | 2484 | 1910 |
| 20 | 1405 | 1116 | 916 | 2006 | 1588 | 1290 | 2722 | 2147 | 1690 | 3561 | 2798 | 2140 |
| 30 | 1658 | 1327 | 1025 | 2373 | 1892 | 1525 | 3220 | 2558 | 1990 | 4197 | 3326 | 2520 |
| 50 | 2024 | 1640 | 1280 | 2911 | 2347 | 1863 | 3964 | 3183 | 2430 | 5184 | 4149 | 3075 |
| 100 | 2569 | 2131 | 1670 | 3732 | 3076 | 2450 | 5125 | 4202 | 3200 | 6749 | 5509 | 4050 |
* NA: Not applicable.
| NUMBER OF APPLIANCES: | TWO OR MORE | |||||||||
| APPLIANCE TYPE: | CATEGORY I | |||||||||
| APPLIANCE VENT CONNECTION: | TYPE B DOUBLE-WALL CONNECTOR | |||||||||
| VENT CONNECTOR CAPACITY | ||||||||||
| TYPE B DOUBLE-WALL VENT AND CONNECTOR DIAMETER - D (inch) | ||||||||||
| 20 | 22 | 24 | ||||||||
| APPLIANCE INPUT RATING LIMITS IN THOUSANDS OF BTU PER HOUR | ||||||||||
| VENT HEIGHT H (feet) |
CONNECTOR RISE R (feet) |
FAN | NAT | FAN | NAT | FAN | NAT | |||
| Min | Max | Max | Min | Max | Max | Min | Max | Max | ||
| 6 | 2 | NA | NA | NA | NA | NA | NA | NA | NA | NA |
| 4 | NA | NA | NA | NA | NA | NA | NA | NA | NA | |
| 6 | NA | NA | NA | NA | NA | NA | NA | NA | NA | |
| 8 | 2 | NA | NA | NA | NA | NA | NA | NA | NA | NA |
| 4 | 471 | 2737 | 1800 | 560 | 3319 | 2180 | 662 | 3957 | 2590 | |
| 6 | 478 | 3018 | 2180 | 568 | 3665 | 2640 | 669 | 4373 | 3130 | |
| 10 | 2 | NA | NA | NA | NA | NA | NA | NA | NA | NA |
| 4 | 486 | 2887 | 1890 | 581 | 3502 | 2280 | 686 | 4175 | 2710 | |
| 6 | 494 | 3169 | 2290 | 589 | 3849 | 2760 | 694 | 4593 | 3270 | |
| 15 | 2 | NA | NA | NA | NA | NA | NA | NA | NA | NA |
| 4 | 523 | 3197 | 2060 | 624 | 3881 | 2490 | 734 | 4631 | 2960 | |
| 6 | 533 | 3470 | 2510 | 634 | 4216 | 3030 | 743 | 5035 | 3600 | |
| 20 | 2 | NA | NA | NA | NA | NA | NA | NA | NA | NA |
| 4 | 554 | 3447 | 2180 | 661 | 4190 | 2630 | 772 | 5005 | 3130 | |
| 6 | 567 | 3708 | 2650 | 671 | 4511 | 3190 | 785 | 5392 | 3790 | |
| 30 | 2 | NA | NA | NA | NA | NA | NA | NA | NA | NA |
| 4 | 619 | 3840 | 2365 | 728 | 4861 | 2860 | 847 | 5606 | 3410 | |
| 6 | 632 | 4080 | 2875 | 741 | 4976 | 3480 | 860 | 5961 | 4150 | |
| 50 | 2 | NA | NA | NA | NA | NA | NA | NA | NA | NA |
| 4 | 580 | 4601 | 2633 | 709 | 5569 | 3185 | 851 | 6633 | 3790 | |
| 6 | 594 | 4808 | 3208 | 724 | 5826 | 3885 | 867 | 6943 | 4620 | |
| 100 | 2 | NA | NA | NA | NA | NA | NA | NA | NA | NA |
| 4 | 523 | 5982 | 2750 | 639 | 7254 | 3330 | 769 | 8650 | 3950 | |
| 6 | 539 | 6143 | 3350 | 654 | 7453 | 4070 | 786 | 8892 | 4810 | |
| COMMON VENT CAPACITY | |||||||||
| TYPE B DOUBLE-WALL COMMON VENT DIAMETER - D (inch) | |||||||||
| 20 | 22 | 24 | |||||||
| COMBINED APPLIANCE INPUT RATING IN THOUSANDS OF BTU PER HOUR | |||||||||
| VENT HEIGHT H (feet) |
FAN +FAN |
FAN +NAT |
NAT +NAT |
FAN +FAN |
FAN +NAT |
NAT +NAT |
FAN +FAN |
FAN +NAT |
NAT +NAT |
| 6 | 2838 | 2180 | 1660 | 3488 | 2677 | 1970 | 4206 | 3226 | 2390 |
| 8 | 3162 | 2439 | 1860 | 3890 | 2998 | 2200 | 4695 | 3616 | 2680 |
| 10 | 3444 | 2665 | 2030 | 4241 | 3278 | 2400 | 5123 | 3957 | 2920 |
| 15 | 4026 | 3133 | 2360 | 4971 | 3862 | 2790 | 6016 | 4670 | 3400 |
| 20 | 4548 | 3552 | 2640 | 5573 | 4352 | 3120 | 6749 | 5261 | 3800 |
| 30 | 5303 | 4193 | 3110 | 6539 | 5157 | 3680 | 7940 | 6247 | 4480 |
| 50 | 6567 | 5240 | 3800 | 8116 | 6458 | 4500 | 9837 | 7813 | 5475 |
| 100 | 8597 | 6986 | 5000 | 10681 | 8648 | 5920 | 13004 | 10499 | 7200 |
* NA: Not applicable.
| NUMBER OF APPLIANCES: | TWO OR MORE | |||||||||||||||
| APPLIANCE TYPE: | CATEGORY I | |||||||||||||||
| APPLIANCE VENT CONNECTION: | SINGLE-WALL METAL CONNECTOR | |||||||||||||||
| VENT CONNECTOR CAPACITY | ||||||||||||||||
| SINGLE-WALL METAL VENT CONNECTOR DIAMETER - D (inch) | ||||||||||||||||
| 3 | 4 | 5 | 6 | 7 | ||||||||||||
| APPLIANCE INPUT RATING LIMITS IN THOUSANDS OF BTU PER HOUR | ||||||||||||||||
| VENT HEIGHT H (feet) |
CONNECTOR RISE R (feet) |
FAN | NAT | FAN | NAT | FAN | NAT | FAN | NAT | FAN | NAT | |||||
| Min | Max | Max | Min | Max | Max | Min | Max | Max | Min | Max | Max | Min | Max | Max | ||
| 6 | 1 | NA | NA | 26 | NA | NA | 46 | NA | NA | 71 | NA | NA | 102 | 207 | 223 | 140 |
| 2 | NA | NA | 31 | NA | NA | 55 | NA | NA | 85 | 168 | 182 | 123 | 215 | 251 | 167 | |
| 3 | NA | NA | 34 | NA | NA | 62 | 121 | 131 | 95 | 175 | 198 | 138 | 222 | 273 | 188 | |
| 8 | 1 | NA | NA | 27 | NA | NA | 48 | NA | NA | 75 | NA | NA | 106 | 226 | 240 | 145 |
| 2 | NA | NA | 32 | NA | NA | 57 | 125 | 126 | 89 | 184 | 193 | 127 | 234 | 266 | 173 | |
| 3 | NA | NA | 35 | NA | NA | 64 | 130 | 138 | 100 | 191 | 208 | 144 | 241 | 287 | 197 | |
| 10 | 1 | NA | NA | 28 | NA | NA | 50 | 119 | 121 | 77 | 182 | 186 | 110 | 240 | 253 | 150 |
| 2 | NA | NA | 33 | 84 | 85 | 59 | 124 | 134 | 91 | 189 | 203 | 132 | 248 | 278 | 183 | |
| 3 | NA | NA | 36 | 89 | 91 | 67 | 129 | 144 | 102 | 197 | 217 | 148 | 257 | 299 | 203 | |
| 15 | 1 | NA | NA | 29 | 79 | 87 | 52 | 116 | 138 | 81 | 177 | 214 | 116 | 238 | 291 | 158 |
| 2 | NA | NA | 34 | 83 | 94 | 62 | 121 | 150 | 97 | 185 | 230 | 138 | 246 | 314 | 189 | |
| 3 | NA | NA | 39 | 87 | 100 | 70 | 127 | 160 | 109 | 193 | 243 | 157 | 255 | 333 | 215 | |
| 20 | 1 | 49 | 56 | 30 | 78 | 97 | 54 | 115 | 152 | 84 | 175 | 238 | 120 | 233 | 325 | 165 |
| 2 | 52 | 59 | 36 | 82 | 103 | 64 | 120 | 163 | 101 | 182 | 252 | 144 | 243 | 346 | 197 | |
| 3 | 55 | 62 | 40 | 87 | 107 | 72 | 125 | 172 | 113 | 190 | 264 | 164 | 252 | 363 | 223 | |
| 30 | 1 | 47 | 60 | 31 | 77 | 110 | 57 | 112 | 175 | 89 | 169 | 278 | 129 | 226 | 380 | 175 |
| 2 | 51 | 62 | 37 | 81 | 115 | 67 | 117 | 185 | 106 | 177 | 290 | 152 | 236 | 397 | 208 | |
| 3 | 54 | 64 | 42 | 85 | 119 | 76 | 122 | 193 | 120 | 185 | 300 | 172 | 244 | 412 | 235 | |
| 50 | 1 | 46 | 69 | 34 | 75 | 128 | 60 | 109 | 207 | 96 | 162 | 336 | 137 | 217 | 460 | 188 |
| 2 | 49 | 71 | 40 | 79 | 132 | 72 | 114 | 215 | 113 | 170 | 345 | 164 | 226 | 473 | 223 | |
| 3 | 52 | 72 | 45 | 83 | 136 | 82 | 119 | 221 | 123 | 178 | 353 | 186 | 235 | 486 | 252 | |
| 100 | 1 | 45 | 79 | 34 | 71 | 150 | 61 | 104 | 249 | 98 | 153 | 424 | 140 | 205 | 585 | 192 |
| 2 | 48 | 80 | 41 | 75 | 153 | 73 | 110 | 255 | 115 | 160 | 428 | 167 | 212 | 593 | 228 | |
| 3 | 51 | 81 | 46 | 79 | 157 | 85 | 114 | 260 | 129 | 168 | 433 | 190 | 222 | 603 | 256 | |
| COMMON VENT CAPACITY | ||||||||||||
| TYPE B DOUBLE-WALL COMMON VENT DIAMETER - D (inch) | ||||||||||||
| 4 | 5 | 6 | 7 | |||||||||
| COMBINED APPLIANCE INPUT RATING IN THOUSANDS OF BTU PER HOUR | ||||||||||||
| VENT HEIGHT H (feet) |
FAN +FAN |
FAN +NAT |
NAT +NAT |
FAN +FAN |
FAN +NAT |
NAT +NAT |
FAN +FAN |
FAN +NAT |
NAT +NAT |
FAN +FAN |
FAN +NAT |
NAT +NAT |
| 6 | NA | 78 | 64 | NA | 113 | 99 | 200 | 158 | 144 | 304 | 244 | 196 |
| 8 | NA | 87 | 71 | NA | 126 | 111 | 218 | 173 | 159 | 331 | 269 | 218 |
| 10 | NA | 94 | 76 | 163 | 137 | 120 | 237 | 189 | 174 | 357 | 292 | 236 |
| 15 | 121 | 108 | 88 | 189 | 159 | 140 | 275 | 221 | 200 | 416 | 343 | 274 |
| 20 | 131 | 118 | 98 | 208 | 177 | 156 | 305 | 247 | 223 | 463 | 383 | 302 |
| 30 | 145 | 132 | 113 | 236 | 202 | 180 | 350 | 286 | 257 | 533 | 446 | 349 |
| 50 | 159 | 145 | 128 | 268 | 233 | 208 | 406 | 337 | 296 | 622 | 529 | 410 |
| 100 | 166 | 153 | NA | 297 | 263 | NA | 469 | 398 | NA | 726 | 633 | 464 |
* NA: Not applicable.
| NUMBER OF APPLIANCES: | TWO OR MORE | |||||||||
| APPLIANCE TYPE: | CATEGORY I | |||||||||
| APPLIANCE VENT CONNECTION: | SINGLE-WALL METAL CONNECTOR | |||||||||
| VENT CONNECTOR CAPACITY | ||||||||||
| SINGLE-WALL METAL VENT CONNECTOR DIAMETER - D (inch) | ||||||||||
| 8 | 9 | 10 | ||||||||
| APPLIANCE INPUT RATING LIMITS IN THOUSANDS OF BTU PER HOUR | ||||||||||
| VENT HEIGHT H (feet) |
CONNECTOR RISE R (feet) |
FAN | NAT | FAN | NAT | FAN | NAT | |||
| Min | Max | Max | Min | Max | Max | Min | Max | Max | ||
| 6 | 1 | 262 | 293 | 183 | 325 | 373 | 234 | 447 | 463 | 286 |
| 2 | 271 | 331 | 219 | 334 | 422 | 281 | 458 | 524 | 344 | |
| 3 | 279 | 361 | 247 | 344 | 462 | 316 | 468 | 574 | 385 | |
| 8 | 1 | 285 | 316 | 191 | 352 | 403 | 244 | 481 | 502 | 299 |
| 2 | 293 | 353 | 228 | 360 | 450 | 292 | 492 | 560 | 355 | |
| 3 | 302 | 381 | 256 | 370 | 489 | 328 | 501 | 609 | 400 | |
| 10 | 1 | 302 | 335 | 196 | 372 | 429 | 252 | 506 | 534 | 308 |
| 2 | 311 | 369 | 235 | 381 | 473 | 302 | 517 | 589 | 368 | |
| 3 | 320 | 398 | 265 | 391 | 511 | 339 | 528 | 637 | 413 | |
| 15 | 1 | 312 | 380 | 208 | 397 | 482 | 266 | 556 | 596 | 324 |
| 2 | 321 | 411 | 248 | 407 | 522 | 317 | 568 | 646 | 387 | |
| 3 | 331 | 438 | 281 | 418 | 557 | 360 | 579 | 690 | 437 | |
| 20 | 1 | 306 | 425 | 217 | 390 | 538 | 276 | 546 | 664 | 336 |
| 2 | 317 | 453 | 259 | 400 | 574 | 331 | 558 | 709 | 403 | |
| 3 | 326 | 476 | 294 | 412 | 607 | 375 | 570 | 750 | 457 | |
| 30 | 1 | 296 | 497 | 230 | 378 | 630 | 294 | 528 | 779 | 358 |
| 2 | 307 | 521 | 274 | 389 | 662 | 349 | 541 | 819 | 425 | |
| 3 | 316 | 542 | 309 | 400 | 690 | 394 | 555 | 855 | 482 | |
| 50 | 1 | 284 | 604 | 245 | 364 | 768 | 314 | 507 | 951 | 384 |
| 2 | 294 | 623 | 293 | 376 | 793 | 375 | 520 | 983 | 458 | |
| 3 | 304 | 640 | 331 | 387 | 816 | 423 | 535 | 1013 | 518 | |
| 100 | 1 | 269 | 774 | 249 | 345 | 993 | 321 | 476 | 1236 | 393 |
| 2 | 279 | 788 | 299 | 358 | 1011 | 383 | 490 | 1259 | 469 | |
| 3 | 289 | 801 | 339 | 368 | 1027 | 431 | 506 | 1280 | 527 | |
| COMMON VENT CAPACITY | |||||||||
| TYPE B DOUBLE-WALL COMMON VENT DIAMETER - D (inch) | |||||||||
| 8 | 9 | 10 | |||||||
| COMBINED APPLIANCE INPUT RATING IN THOUSANDS OF BTU PER HOUR | |||||||||
| VENT HEIGHT H (feet) |
FAN +FAN |
FAN +NAT |
NAT +NAT |
FAN +FAN |
FAN +NAT |
NAT +NAT |
FAN +FAN |
FAN +NAT |
NAT +NAT |
| 6 | 398 | 310 | 257 | 541 | 429 | 332 | 665 | 515 | 407 |
| 8 | 436 | 342 | 285 | 592 | 473 | 373 | 730 | 569 | 460 |
| 10 | 467 | 369 | 309 | 638 | 512 | 398 | 787 | 617 | 487 |
| 15 | 544 | 434 | 357 | 738 | 599 | 456 | 905 | 718 | 553 |
| 20 | 606 | 487 | 395 | 824 | 673 | 512 | 1013 | 808 | 626 |
| 30 | 703 | 570 | 459 | 958 | 790 | 593 | 1183 | 952 | 723 |
| 50 | 833 | 686 | 535 | 1139 | 954 | 689 | 1418 | 1157 | 838 |
| 100 | 999 | 846 | 606 | 1378 | 1185 | 780 | 1741 | 1459 | 948 |
| NUMBER OF APPLIANCES: | TWO OR MORE | |||||||||||||||
| APPLIANCE TYPE: | CATEGORY I | |||||||||||||||
| APPLIANCE VENT CONNECTION: | TYPE B DOUBLE-WALL CONNECTOR | |||||||||||||||
| VENT CONNECTOR CAPACITY | ||||||||||||||||
| TYPE B DOUBLE-WALL VENT CONNECTOR DIAMETER - D (inch) | ||||||||||||||||
| 3 | 4 | 5 | 6 | 7 | ||||||||||||
| APPLIANCE INPUT RATING LIMITS IN THOUSANDS OF BTU PER HOUR | ||||||||||||||||
| VENT HEIGHT H (feet) |
CONNECTOR RISE R (feet) |
FAN | NAT | FAN | NAT | FAN | NAT | FAN | NAT | FAN | NAT | |||||
| Min | Max | Max | Min | Max | Max | Min | Max | Max | Min | Max | Max | Min | Max | Max | ||
| 6 | 1 | 24 | 33 | 21 | 39 | 62 | 40 | 52 | 106 | 67 | 65 | 194 | 101 | 87 | 274 | 141 |
| 2 | 26 | 43 | 28 | 41 | 79 | 52 | 53 | 133 | 85 | 67 | 230 | 124 | 89 | 324 | 173 | |
| 3 | 27 | 49 | 34 | 42 | 92 | 61 | 55 | 155 | 97 | 69 | 262 | 143 | 91 | 369 | 203 | |
| 8 | 1 | 24 | 39 | 22 | 39 | 72 | 41 | 55 | 117 | 69 | 71 | 213 | 105 | 94 | 304 | 148 |
| 2 | 26 | 47 | 29 | 40 | 87 | 53 | 57 | 140 | 86 | 73 | 246 | 127 | 97 | 350 | 179 | |
| 3 | 27 | 52 | 34 | 42 | 97 | 62 | 59 | 159 | 98 | 75 | 269 | 145 | 99 | 383 | 206 | |
| 10 | 1 | 24 | 42 | 22 | 38 | 80 | 42 | 55 | 130 | 71 | 74 | 232 | 108 | 101 | 324 | 153 |
| 2 | 26 | 50 | 29 | 40 | 93 | 54 | 57 | 153 | 87 | 76 | 261 | 129 | 103 | 366 | 184 | |
| 3 | 27 | 55 | 35 | 41 | 105 | 63 | 58 | 170 | 100 | 78 | 284 | 148 | 106 | 397 | 209 | |
| 15 | 1 | 24 | 48 | 23 | 38 | 93 | 44 | 54 | 154 | 74 | 72 | 277 | 114 | 100 | 384 | 164 |
| 2 | 25 | 55 | 31 | 39 | 105 | 55 | 56 | 174 | 89 | 74 | 299 | 134 | 103 | 419 | 192 | |
| 3 | 26 | 59 | 35 | 41 | 115 | 64 | 57 | 189 | 102 | 76 | 319 | 153 | 105 | 448 | 215 | |
| 20 | 1 | 24 | 52 | 24 | 37 | 102 | 46 | 53 | 172 | 77 | 71 | 313 | 119 | 98 | 437 | 173 |
| 2 | 25 | 58 | 31 | 39 | 114 | 56 | 55 | 190 | 91 | 73 | 335 | 138 | 101 | 467 | 199 | |
| 3 | 26 | 63 | 35 | 40 | 123 | 65 | 57 | 204 | 104 | 75 | 353 | 157 | 104 | 493 | 222 | |
| 30 | 1 | 24 | 54 | 25 | 37 | 111 | 48 | 52 | 192 | 82 | 69 | 357 | 127 | 96 | 504 | 187 |
| 2 | 25 | 60 | 32 | 38 | 122 | 58 | 54 | 208 | 95 | 72 | 376 | 145 | 99 | 531 | 209 | |
| 3 | 26 | 64 | 36 | 40 | 131 | 66 | 56 | 221 | 107 | 74 | 392 | 163 | 101 | 554 | 233 | |
| 50 | 1 | 23 | 51 | 25 | 36 | 116 | 51 | 51 | 209 | 89 | 67 | 405 | 143 | 92 | 582 | 213 |
| 2 | 24 | 59 | 32 | 37 | 127 | 61 | 53 | 225 | 102 | 70 | 421 | 161 | 95 | 604 | 235 | |
| 3 | 26 | 64 | 36 | 39 | 135 | 69 | 55 | 237 | 115 | 72 | 435 | 180 | 98 | 624 | 260 | |
| 100 | 1 | 23 | 46 | 24 | 35 | 108 | 50 | 49 | 208 | 92 | 65 | 428 | 155 | 88 | 640 | 237 |
| 2 | 24 | 53 | 31 | 37 | 120 | 60 | 51 | 224 | 105 | 67 | 444 | 174 | 92 | 660 | 260 | |
| 3 | 25 | 59 | 35 | 38 | 130 | 68 | 53 | 237 | 118 | 69 | 458 | 193 | 94 | 679 | 285 | |
| COMMON VENT CAPACITY | |||||||||||||||
| MINIMUM INTERNAL AREA OF MASONRY CHIMNEY FLUE (square inches) | |||||||||||||||
| 12 | 19 | 28 | 38 | 50 | |||||||||||
| COMBINED APPLIANCE INPUT RATING IN THOUSANDS OF BTU PER HOUR | |||||||||||||||
| VENT HEIGHT H (feet) |
FAN +FAN |
FAN +NAT |
NAT +NAT |
FAN +FAN |
FAN +NAT |
NAT +NAT |
FAN +FAN |
FAN +NAT |
NAT +NAT |
FAN +FAN |
FAN +NAT |
NAT +NAT |
FAN +FAN |
FAN +NAT |
NAT +NAT |
| 6 | NA | 74 | 25 | NA | 119 | 46 | NA | 178 | 71 | NA | 257 | 103 | NA | 351 | 143 |
| 8 | NA | 80 | 28 | NA | 130 | 53 | NA | 193 | 82 | NA | 279 | 119 | NA | 384 | 163 |
| 10 | NA | 84 | 31 | NA | 138 | 56 | NA | 207 | 90 | NA | 299 | 131 | NA | 409 | 177 |
| 15 | NA | NA | 36 | NA | 152 | 67 | NA | 233 | 106 | NA | 334 | 152 | 523 | 467 | 212 |
| 20 | NA | NA | 41 | NA | NA | 75 | NA | 250 | 122 | NA | 368 | 172 | 565 | 508 | 243 |
| 30 | NA | NA | NA | NA | NA | NA | NA | 270 | 137 | NA | 404 | 198 | 615 | 564 | 278 |
| 50 | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | 620 | 328 |
| 100 | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | 348 |
* NA: Not applicable.
| NUMBER OF APPLIANCES: | TWO OR MORE | |||||||||
| APPLIANCE TYPE: | CATEGORY I | |||||||||
| APPLIANCE VENT CONNECTION: | TYPE B DOUBLE-WALL CONNECTOR | |||||||||
| VENT CONNECTOR CAPACITY | ||||||||||
| TYPE B DOUBLE-WALL VENT CONNECTOR DIAMETER - D (inch) | ||||||||||
| 8 | 9 | 10 | ||||||||
| APPLIANCE INPUT RATING LIMITS IN THOUSANDS OF BTU PER HOUR | ||||||||||
| VENT HEIGHT H (feet) |
CONNECTOR RISE R (feet) |
FAN | NAT | FAN | NAT | FAN | NAT | |||
| Min | Max | Max | Min | Max | Max | Min | Max | Max | ||
| 6 | 1 | 104 | 370 | 201 | 124 | 479 | 253 | 145 | 599 | 319 |
| 2 | 107 | 436 | 232 | 127 | 562 | 300 | 148 | 694 | 378 | |
| 3 | 109 | 491 | 270 | 129 | 633 | 349 | 151 | 795 | 439 | |
| 8 | 1 | 113 | 414 | 210 | 134 | 539 | 267 | 156 | 682 | 335 |
| 2 | 116 | 473 | 240 | 137 | 615 | 311 | 160 | 776 | 394 | |
| 3 | 119 | 517 | 276 | 139 | 672 | 358 | 163 | 848 | 452 | |
| 10 | 1 | 120 | 444 | 216 | 142 | 582 | 277 | 165 | 739 | 348 |
| 2 | 123 | 498 | 247 | 145 | 652 | 321 | 168 | 825 | 407 | |
| 3 | 126 | 540 | 281 | 147 | 705 | 366 | 171 | 893 | 463 | |
| 15 | 1 | 125 | 511 | 229 | 153 | 658 | 297 | 184 | 824 | 375 |
| 2 | 128 | 558 | 260 | 156 | 718 | 339 | 187 | 900 | 432 | |
| 3 | 131 | 597 | 292 | 159 | 760 | 382 | 190 | 960 | 486 | |
| 20 | 1 | 123 | 584 | 239 | 150 | 752 | 312 | 180 | 943 | 397 |
| 2 | 126 | 625 | 270 | 153 | 805 | 354 | 184 | 1011 | 452 | |
| 3 | 129 | 661 | 301 | 156 | 851 | 396 | 187 | 1067 | 505 | |
| 30 | 1 | 119 | 680 | 255 | 145 | 883 | 337 | 175 | 1115 | 432 |
| 2 | 122 | 715 | 287 | 149 | 928 | 378 | 179 | 1171 | 484 | |
| 3 | 125 | 746 | 317 | 152 | 968 | 418 | 182 | 1220 | 535 | |
| 50 | 1 | 115 | 798 | 294 | 140 | 1049 | 392 | 168 | 1334 | 506 |
| 2 | 118 | 827 | 326 | 143 | 1085 | 433 | 172 | 1379 | 558 | |
| 3 | 121 | 854 | 357 | 147 | 1118 | 474 | 176 | 1421 | 611 | |
| 100 | 1 | 109 | 907 | 334 | 134 | 1222 | 454 | 161 | 1589 | 596 |
| 2 | 113 | 933 | 368 | 138 | 1253 | 497 | 165 | 1626 | 651 | |
| 3 | 116 | 956 | 399 | 141 | 1282 | 540 | 169 | 1661 | 705 | |
| COMMON VENT CAPACITY | |||||||||
| MINIMUM INTERNAL AREA OF MASONRY CHIMNEY FLUE (square inches) | |||||||||
| 63 | 78 | 113 | |||||||
| COMBINED APPLIANCE INPUT RATING IN THOUSANDS OF BTU PER HOUR | |||||||||
| VENT HEIGHT H (feet) |
FAN +FAN |
FAN +NAT |
NAT +NAT |
FAN +FAN |
FAN +NAT |
NAT +NAT |
FAN +FAN |
FAN +NAT |
NAT +NAT |
| 6 | NA | 458 | 188 | NA | 582 | 246 | 1041 | 853 | NA |
| 8 | NA | 501 | 218 | 724 | 636 | 278 | 1144 | 937 | 408 |
| 10 | 606 | 538 | 236 | 776 | 686 | 302 | 1226 | 1010 | 454 |
| 15 | 682 | 611 | 283 | 874 | 781 | 365 | 1374 | 1156 | 546 |
| 20 | 742 | 668 | 325 | 955 | 858 | 419 | 1513 | 1286 | 648 |
| 30 | 816 | 747 | 381 | 1062 | 969 | 496 | 1702 | 1473 | 749 |
| 50 | 879 | 831 | 461 | 1165 | 1089 | 606 | 1905 | 1692 | 922 |
| 100 | NA | NA | 499 | NA | NA | 669 | 2053 | 1921 | 1058 |
* NA: Not applicable.
| NUMBER OF APPLIANCES: | TWO OR MORE | |||||||||||||||
| APPLIANCE TYPE: | CATEGORY I | |||||||||||||||
| APPLIANCE VENT CONNECTION: | SINGLE-WALL METAL CONNECTOR | |||||||||||||||
| VENT CONNECTOR CAPACITY | ||||||||||||||||
| SINGLE-WALL METAL VENT CONNECTOR DIAMETER - D (inch) | ||||||||||||||||
| 3 | 4 | 5 | 6 | 7 | ||||||||||||
| APPLIANCE INPUT RATING LIMITS IN THOUSANDS OF BTU PER HOUR | ||||||||||||||||
| VENT HEIGHT H (feet) |
CONNECTOR RISE R (feet) |
FAN | NAT | FAN | NAT | FAN | NAT | FAN | NAT | FAN | NAT | |||||
| Min | Max | Max | Min | Max | Max | Min | Max | Max | Min | Max | Max | Min | Max | Max | ||
| 6 | 1 | NA | NA | 21 | NA | NA | 39 | NA | NA | 66 | 179 | 191 | 100 | 231 | 271 | 140 |
| 2 | NA | NA | 28 | NA | NA | 52 | NA | NA | 84 | 186 | 227 | 123 | 239 | 321 | 172 | |
| 3 | NA | NA | 34 | NA | NA | 61 | 134 | 153 | 97 | 193 | 258 | 142 | 247 | 365 | 202 | |
| 8 | 1 | NA | NA | 21 | NA | NA | 40 | NA | NA | 68 | 195 | 208 | 103 | 250 | 298 | 146 |
| 2 | NA | NA | 28 | NA | NA | 52 | 137 | 139 | 85 | 202 | 240 | 125 | 258 | 343 | 177 | |
| 3 | NA | NA | 34 | NA | NA | 62 | 143 | 156 | 98 | 210 | 264 | 145 | 266 | 376 | 205 | |
| 10 | 1 | NA | NA | 22 | NA | NA | 41 | 130 | 151 | 70 | 202 | 225 | 106 | 267 | 316 | 151 |
| 2 | NA | NA | 29 | NA | NA | 53 | 136 | 150 | 86 | 210 | 255 | 128 | 276 | 358 | 181 | |
| 3 | NA | NA | 34 | 97 | 102 | 62 | 143 | 166 | 99 | 217 | 277 | 147 | 284 | 389 | 207 | |
| 15 | 1 | NA | NA | 23 | NA | NA | 43 | 129 | 151 | 73 | 199 | 271 | 112 | 268 | 376 | 161 |
| 2 | NA | NA | 30 | 92 | 103 | 54 | 135 | 170 | 88 | 207 | 295 | 132 | 277 | 411 | 189 | |
| 3 | NA | NA | 34 | 96 | 112 | 63 | 141 | 185 | 101 | 215 | 315 | 151 | 286 | 439 | 213 | |
| 20 | 1 | NA | NA | 23 | 87 | 99 | 45 | 128 | 167 | 76 | 197 | 303 | 117 | 265 | 425 | 169 |
| 2 | NA | NA | 30 | 91 | 111 | 55 | 134 | 185 | 90 | 205 | 325 | 136 | 274 | 455 | 195 | |
| 3 | NA | NA | 35 | 96 | 119 | 64 | 140 | 199 | 103 | 213 | 343 | 154 | 282 | 481 | 219 | |
| 30 | 1 | NA | NA | 24 | 86 | 108 | 47 | 126 | 187 | 80 | 193 | 347 | 124 | 259 | 492 | 183 |
| 2 | NA | NA | 31 | 91 | 119 | 57 | 132 | 203 | 93 | 201 | 366 | 142 | 269 | 518 | 205 | |
| 3 | NA | NA | 35 | 95 | 127 | 65 | 138 | 216 | 105 | 209 | 381 | 160 | 277 | 540 | 229 | |
| 50 | 1 | NA | NA | 24 | 85 | 113 | 50 | 124 | 204 | 87 | 188 | 392 | 139 | 252 | 567 | 208 |
| 2 | NA | NA | 31 | 89 | 123 | 60 | 130 | 218 | 100 | 196 | 408 | 158 | 262 | 588 | 230 | |
| 3 | NA | NA | 35 | 94 | 131 | 68 | 136 | 231 | 112 | 205 | 422 | 176 | 271 | 607 | 255 | |
| 100 | 1 | NA | NA | 23 | 84 | 104 | 49 | 122 | 200 | 89 | 182 | 410 | 151 | 243 | 617 | 232 |
| 2 | NA | NA | 30 | 88 | 115 | 59 | 127 | 215 | 102 | 190 | 425 | 169 | 253 | 636 | 254 | |
| 3 | NA | NA | 34 | 93 | 124 | 67 | 133 | 228 | 115 | 199 | 438 | 188 | 262 | 654 | 279 | |
| COMMON VENT CAPACITY | |||||||||||||||
| MINIMUM INTERNAL AREA OF MASONRY CHIMNEY FLUE (square inches) | |||||||||||||||
| 12 | 19 | 28 | 38 | 50 | |||||||||||
| COMBINED APPLIANCE INPUT RATING IN THOUSANDS OF BTU PER HOUR | |||||||||||||||
| VENT HEIGHT H (feet) |
FAN +FAN |
FAN +NAT |
NAT +NAT |
FAN +FAN |
FAN +NAT |
NAT +NAT |
FAN +FAN |
FAN +NAT |
NAT +NAT |
FAN +FAN |
FAN +NAT |
NAT +NAT |
FAN +FAN |
FAN +NAT |
NAT +NAT |
| 6 | NA | NA | 25 | NA | 118 | 45 | NA | 176 | 71 | NA | 255 | 102 | NA | 348 | 142 |
| 8 | NA | NA | 28 | NA | 128 | 52 | NA | 190 | 81 | NA | 276 | 118 | NA | 380 | 162 |
| 10 | NA | NA | 31 | NA | 136 | 56 | NA | 205 | 89 | NA | 295 | 129 | NA | 405 | 175 |
| 15 | NA | NA | 36 | NA | NA | 66 | NA | 230 | 105 | NA | 335 | 150 | NA | 400 | 210 |
| 20 | NA | NA | NA | NA | NA | 74 | NA | 247 | 120 | NA | 362 | 170 | NA | 503 | 240 |
| 30 | NA | NA | NA | NA | NA | NA | NA | NA | 135 | NA | 398 | 195 | NA | 558 | 275 |
| 50 | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | 612 | 325 |
| 100 | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA |
* NA: Not applicable.
| NUMBER OF APPLIANCES: | TWO OR MORE | |||||||||
| APPLIANCE TYPE: | CATEGORY I | |||||||||
| APPLIANCE VENT CONNECTION: | SINGLE-WALL METAL CONNECTOR | |||||||||
| VENT CONNECTOR CAPACITY | ||||||||||
| SINGLE-WALL METAL VENT CONNECTOR DIAMETER - D (inch) | ||||||||||
| 8 | 9 | 10 | ||||||||
| APPLIANCE INPUT RATING LIMITS IN THOUSANDS OF BTU PER HOUR | ||||||||||
| VENT HEIGHT H (feet) |
CONNECTOR RISE R (feet) |
FAN | NAT | FAN | NAT | FAN | NAT | |||
| Min | Max | Max | Min | Max | Max | Min | Max | Max | ||
| 6 | 1 | 292 | 366 | 200 | 362 | 474 | 252 | 499 | 594 | 316 |
| 2 | 301 | 432 | 231 | 373 | 557 | 299 | 509 | 696 | 376 | |
| 3 | 309 | 491 | 269 | 381 | 634 | 348 | 519 | 793 | 437 | |
| 8 | 1 | 313 | 407 | 207 | 387 | 530 | 263 | 529 | 672 | 331 |
| 2 | 323 | 465 | 238 | 397 | 607 | 309 | 540 | 766 | 391 | |
| 3 | 332 | 509 | 274 | 407 | 663 | 356 | 551 | 838 | 450 | |
| 10 | 1 | 333 | 434 | 213 | 410 | 571 | 273 | 558 | 727 | 343 |
| 2 | 343 | 489 | 244 | 420 | 640 | 317 | 569 | 813 | 403 | |
| 3 | 352 | 530 | 279 | 430 | 694 | 363 | 580 | 880 | 459 | |
| 15 | 1 | 349 | 502 | 225 | 445 | 646 | 291 | 623 | 808 | 366 |
| 2 | 359 | 548 | 256 | 456 | 706 | 334 | 634 | 884 | 424 | |
| 3 | 368 | 586 | 289 | 466 | 755 | 378 | 646 | 945 | 479 | |
| 20 | 1 | 345 | 569 | 235 | 439 | 734 | 306 | 614 | 921 | 387 |
| 2 | 355 | 610 | 266 | 450 | 787 | 348 | 627 | 986 | 443 | |
| 3 | 365 | 644 | 298 | 461 | 831 | 391 | 639 | 1042 | 496 | |
| 30 | 1 | 338 | 665 | 250 | 430 | 864 | 330 | 600 | 1089 | 421 |
| 2 | 348 | 699 | 282 | 442 | 908 | 372 | 613 | 1145 | 473 | |
| 3 | 358 | 729 | 312 | 452 | 946 | 412 | 626 | 1193 | 524 | |
| 50 | 1 | 328 | 778 | 287 | 417 | 1022 | 383 | 582 | 1302 | 492 |
| 2 | 339 | 806 | 320 | 429 | 1058 | 425 | 596 | 1346 | 545 | |
| 3 | 349 | 831 | 351 | 440 | 1090 | 466 | 610 | 1386 | 597 | |
| 100 | 1 | 315 | 875 | 328 | 402 | 1181 | 444 | 560 | 1537 | 580 |
| 2 | 326 | 899 | 361 | 415 | 1210 | 488 | 575 | 1570 | 634 | |
| 3 | 337 | 921 | 392 | 427 | 1238 | 529 | 589 | 1604 | 687 | |
| COMMON VENT CAPACITY | |||||||||
| MINIMUM INTERNAL AREA OF MASONRY CHIMNEY FLUE (square inches) | |||||||||
| 63 | 78 | 113 | |||||||
| COMBINED APPLIANCE INPUT RATING IN THOUSANDS OF BTU PER HOUR | |||||||||
| VENT HEIGHT H (feet) |
FAN +FAN |
FAN +NAT |
NAT +NAT |
FAN +FAN |
FAN +NAT |
NAT +NAT |
FAN +FAN |
FAN +NAT |
NAT +NAT |
| 6 | NA | 455 | 187 | NA | 579 | 245 | NA | 846 | NA |
| 8 | NA | 497 | 217 | NA | 633 | 277 | 1136 | 928 | 405 |
| 10 | NA | 532 | 234 | 771 | 680 | 300 | 1216 | 1000 | 450 |
| 15 | 677 | 602 | 280 | 866 | 772 | 360 | 1359 | 1139 | 540 |
| 20 | 765 | 661 | 321 | 947 | 849 | 415 | 1495 | 1264 | 640 |
| 30 | 808 | 739 | 377 | 1052 | 957 | 490 | 1682 | 1447 | 740 |
| 50 | NA | 821 | 456 | 1152 | 1076 | 600 | 1879 | 1672 | 910 |
| 100 | NA | NA | 494 | NA | NA | 663 | 2006 | 1885 | 1046 |
* NA: Not applicable.
| NUMBER OF APPLIANCES: | TWO OR MORE | ||||||
| APPLIANCE TYPE: | DRAFT HOOD-EQUIPMENT | ||||||
| APPLIANCE VENT CONNECTION: | DIRECTTO PIPE OR VENT | ||||||
| VENT CONNECTOR CAPACITY | |||||||
| VENT CONNECTOR DIAMETER - D (inch) | |||||||
| TOTAL VENT HEIGHT H (feet) |
CONNECTOR RISE R (feet) |
3 | 4 | 5 | 6 | 7 | 8 |
| APPLIANCE INPUT RATING IN THOUSANDS OF BTU PER HOUR | |||||||
| 6-8 | 1 | 21 | 40 | 68 | 102 | 146 | 205 |
| 2 | 28 | 53 | 86 | 124 | 178 | 235 | |
| 3 | 34 | 61 | 98 | 147 | 204 | 275 | |
| 15 | 1 | 23 | 44 | 77 | 117 | 179 | 240 |
| 2 | 30 | 56 | 92 | 134 | 194 | 265 | |
| 3 | 35 | 64 | 102 | 155 | 216 | 298 | |
| 30 and up |
1 | 25 | 49 | 84 | 129 | 190 | 270 |
| 2 | 31 | 58 | 97 | 145 | 211 | 295 | |
| 3 | 36 | 68 | 107 | 164 | 232 | 321 | |
| COMMON VENT CAPACITY | |||||||
| COMMON VENT DIAMETER - D (inch) | |||||||
| TOTAL VENT HEIGHT H (feet) |
4 | 5 | 6 | 7 | 8 | 10 | 12 |
| COMBINED APPLIANCE INPUT RATING IN THOUSANDS OF BTU PER HOUR | |||||||
| 6 | 48 | 78 | 111 | 155 | 205 | 320 | NA |
| 8 | 55 | 89 | 128 | 175 | 234 | 365 | 505 |
| 10 | 59 | 95 | 136 | 190 | 250 | 395 | 560 |
| 15 | 71 | 115 | 168 | 228 | 305 | 480 | 690 |
| 20 | 80 | 129 | 186 | 260 | 340 | 550 | 790 |
| 30 | NA | 147 | 215 | 300 | 400 | 650 | 940 |
| 50 | NA | NA | NA | 360 | 490 | 810 | 1190 |
* NA: Not applicable.
| NUMBER OF APPLIANCES: | TWO OR MORE | |||||||
| APPLIANCE TYPE: | NAT + NAT | |||||||
| APPLIANCE VENT CONNECTION: | TYPE B DOUBLE-WALL CONNECTOR | |||||||
| COMBINED APPLIANCE MAXIMUM INPUT RATING IN THOUSANDS OF BTU PER HOUR | ||||||||
| VENT HEIGHT H (feet) |
INTERNAL AREA OF CHIMNEY (square inches) | |||||||
| 12 | 19 | 28 | 38 | 50 | 63 | 78 | 113 | |
| 6 | 25 | 46 | 71 | 103 | 143 | 188 | 246 | NA |
| 8 | 28 | 53 | 82 | 119 | 163 | 218 | 278 | 408 |
| 10 | 31 | 56 | 90 | 131 | 177 | 236 | 302 | 454 |
| 15 | NA | 67 | 106 | 152 | 212 | 283 | 365 | 546 |
| 20 | NA | NA | NA | NA | NA | 325 | 419 | 648 |
| 30 | NA | NA | NA | NA | NA | NA | 496 | 749 |
| 50 | NA | NA | NA | NA | NA | NA | NA | 922 |
| 100 | NA | NA | NA | NA | NA | NA | NA | NA |
* NA: Not applicable.
| NUMBER OF APPLIANCES: | TWO OR MORE | |||||||
| APPLIANCE TYPE: | NAT + NAT | |||||||
| APPLIANCE VENT CONNECTION: | TYPE B DOUBLE-WALL CONNECTOR | |||||||
| MINIMUM ALLOWABLE INPUT RATING OF SPACE-HEATING APPLIANCE IN THOUSANDS OF BTU PER HOUR | ||||||||
| VENT HEIGHT H (feet) |
INTERNAL AREA OF CHIMNEY (square inches) | |||||||
| 12 | 19 | 28 | 38 | 50 | 63 | 78 | 113 | |
| Local 99% winter design temperature: 37°F or greater | ||||||||
| 6 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | NA |
| 8 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 |
| 10 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 |
| 15 | NA | 0 | 0 | 0 | 0 | 0 | 0 | 0 |
| 20 | NA | NA | NA | NA | NA | 184 | 0 | 0 |
| 30 | NA | NA | NA | NA | NA | 393 | 334 | 0 |
| 50 | NA | NA | NA | NA | NA | NA | NA | 579 |
| 100 | NA | NA | NA | NA | NA | NA | NA | NA |
| Local 99% winter design temperature: 27°F to 36°F | ||||||||
| 6 | 0 | 0 | 68 | NA | NA | 180 | 212 | NA |
| 8 | 0 | 0 | 82 | NA | NA | 187 | 214 | 263 |
| 10 | 0 | 51 | NA | NA | NA | 201 | 225 | 265 |
| 15 | NA | NA | NA | NA | NA | 253 | 274 | 305 |
| 20 | NA | NA | NA | NA | NA | 307 | 330 | 362 |
| 30 | NA | NA | NA | NA | NA | NA | 445 | 485 |
| 50 | NA | NA | NA | NA | NA | NA | NA | 763 |
| 100 | NA | NA | NA | NA | NA | NA | NA | NA |
| Local 99% winter design temperature: 17°F to 26°F | ||||||||
| 6 | NA | NA | NA | NA | NA | NA | NA | NA |
| 8 | NA | NA | NA | NA | NA | NA | 264 | 352 |
| 10 | NA | NA | NA | NA | NA | NA | 278 | 358 |
| 15 | NA | NA | NA | NA | NA | NA | 331 | 398 |
| 20 | NA | NA | NA | NA | NA | NA | 387 | 457 |
| 30 | NA | NA | NA | NA | NA | NA | NA | 581 |
| 50 | NA | NA | NA | NA | NA | NA | NA | 862 |
| 100 | NA | NA | NA | NA | NA | NA | NA | NA |
| Local 99% winter design temperature: 5°F to 16°F | ||||||||
| 6 | NA | NA | NA | NA | NA | NA | NA | NA |
| 8 | NA | NA | NA | NA | NA | NA | NA | NA |
| 10 | NA | NA | NA | NA | NA | NA | NA | 430 |
| 15 | NA | NA | NA | NA | NA | NA | NA | 485 |
| 20 | NA | NA | NA | NA | NA | NA | NA | 547 |
| 30 | NA | NA | NA | NA | NA | NA | NA | 682 |
| 50 | NA | NA | NA | NA | NA | NA | NA | NA |
| 100 | NA | NA | NA | NA | NA | NA | NA | NA |
| Local 99% winter design temperature: 4°F or lower Not recommended for any vent configurations |
||||||||
Notes:
- 1 See Figure 803.1.2(6) for a map showing local 99 percent winter design temperatures in the United States.
- 2 NA: Not applicable.
| NUMBER OF APPLIANCES: | TWO OR MORE | |||||||
| APPLIANCE TYPE: | FAN + NAT | |||||||
| APPLIANCE VENT CONNECTION: | TYPE B DOUBLE-WALL CONNECTOR | |||||||
| COMBINED APPLIANCE MAXIMUM INPUT RATING IN THOUSANDS OF BTU PER HOUR | ||||||||
| VENT HEIGHT H (feet) |
INTERNAL AREA OF CHIMNEY (square inches) | |||||||
| 12 | 19 | 28 | 38 | 50 | 63 | 78 | 113 | |
| 6 | 74 | 119 | 178 | 257 | 351 | 458 | 582 | 853 |
| 8 | 80 | 130 | 193 | 279 | 384 | 501 | 636 | 937 |
| 10 | 84 | 138 | 207 | 299 | 409 | 538 | 686 | 1010 |
| 15 | NA | 152 | 233 | 334 | 467 | 611 | 781 | 1156 |
| 20 | NA | NA | 250 | 368 | 508 | 668 | 858 | 1286 |
| 30 | NA | NA | NA | 404 | 564 | 747 | 969 | 1473 |
| 50 | NA | NA | NA | NA | NA | 831 | 1089 | 1692 |
| 100 | NA | NA | NA | NA | NA | NA | NA | 1921 |
* NA: Not applicable.
| NUMBER OF APPLIANCES: | TWO OR MORE | |||||||
| APPLIANCE TYPE: | FAN + NAT | |||||||
| APPLIANCE VENT CONNECTION: | TYPE B DOUBLE-WALL CONNECTOR | |||||||
| MINIMUM ALLOWABLE INPUT RATING OF SPACE-HEATING APPLIANCE IN THOUSANDS OF BTU PER HOUR | ||||||||
| VENT HEIGHT H (feet) |
INTERNAL AREA OF CHIMNEY (square inches) | |||||||
| 12 | 19 | 28 | 38 | 50 | 63 | 78 | 113 | |
| Local 99% winter design temperature: 37°F or greater | ||||||||
| 6 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 |
| 8 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 |
| 10 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 |
| 15 | NA | 0 | 0 | 0 | 0 | 0 | 0 | 0 |
| 20 | NA | NA | 123 | 190 | 249 | 184 | 0 | 0 |
| 30 | NA | NA | NA | 334 | 398 | 393 | 334 | 0 |
| 50 | NA | NA | NA | NA | NA | 714 | 707 | 579 |
| 100 | NA | NA | NA | NA | NA | NA | NA | 1600 |
| Local 99% winter design temperature: 27°F to 36°F | ||||||||
| 6 | 0 | 0 | 68 | 116 | 156 | 180 | 212 | 266 |
| 8 | 0 | 0 | 82 | 127 | 167 | 187 | 214 | 263 |
| 10 | 0 | 51 | 97 | 141 | 183 | 201 | 225 | 265 |
| 15 | NA | 111 | 142 | 183 | 233 | 253 | 274 | 305 |
| 20 | NA | NA | 187 | 230 | 284 | 307 | 330 | 362 |
| 30 | NA | NA | NA | 330 | 319 | 419 | 445 | 485 |
| 50 | NA | NA | NA | NA | NA | 672 | 705 | 763 |
| 100 | NA | NA | NA | NA | NA | NA | NA | 1554 |
| Local 99% winter design temperature: 17°F to 26°F | ||||||||
| 6 | 0 | 55 | 99 | 141 | 182 | 215 | 259 | 349 |
| 8 | 52 | 74 | 111 | 154 | 197 | 226 | 264 | 352 |
| 10 | NA | 90 | 125 | 169 | 214 | 245 | 278 | 358 |
| 15 | NA | NA | 167 | 212 | 263 | 296 | 331 | 398 |
| 20 | NA | NA | 212 | 258 | 316 | 352 | 387 | 457 |
| 30 | NA | NA | NA | 362 | 429 | 470 | 507 | 581 |
| 50 | NA | NA | NA | NA | NA | 723 | 766 | 862 |
| 100 | NA | NA | NA | NA | NA | NA | NA | 1669 |
| Local 99% winter design temperature: 5°F to 16°F | ||||||||
| 6 | NA | 78 | 121 | 166 | 214 | 252 | 301 | 416 |
| 8 | NA | 94 | 135 | 182 | 230 | 269 | 312 | 423 |
| 10 | NA | 111 | 149 | 198 | 250 | 289 | 331 | 430 |
| 15 | NA | NA | 193 | 247 | 305 | 346 | 393 | 485 |
| 20 | NA | NA | NA | 293 | 360 | 408 | 450 | 547 |
| 30 | NA | NA | NA | 377 | 450 | 531 | 580 | 682 |
| 50 | NA | NA | NA | NA | NA | 797 | 853 | 972 |
| 100 | NA | NA | NA | NA | NA | NA | NA | 1833 |
| Local 99% winter design temperature: -10°F to 4°F | ||||||||
| 6 | NA | NA | 145 | 196 | 249 | 296 | 349 | 484 |
| 8 | NA | NA | 159 | 213 | 269 | 320 | 371 | 494 |
| 10 | NA | NA | 175 | 231 | 292 | 339 | 397 | 513 |
| 15 | NA | NA | NA | 283 | 351 | 404 | 457 | 586 |
| 20 | NA | NA | NA | 333 | 408 | 468 | 528 | 650 |
| 30 | NA | NA | NA | NA | NA | 603 | 667 | 805 |
| 50 | NA | NA | NA | NA | NA | NA | 955 | 1003 |
| 100 | NA | NA | NA | NA | NA | NA | NA | NA |
| Local 99% winter design temperature: -11°F or lower Not recommended for any vent configurations |
||||||||
Notes:
- 1 See Figure 803.1.2(6) for a map showing local 99 percent winter design temperatures in the United States.
- 2 NA: Not applicable.
The
maximum vent connector horizontal length shall be 18
inches per inch (18 mm/mm) of connector diameter as
shown in Table 803.2.1, or as permitted by Section
803.2.2. [NFPA 54:13.2.2]
For SI units: 1 inch = 25.4 mm, 1 foot = 304.8 mm
| CONNECTOR DIAMETER (inches) |
MAXIMUM CONNECTOR HORIZONTAL LENGTH (feet) |
| 3 | 41/2 |
| 4 | 6 |
| 5 | 71/2 |
| 6 | 9 |
| 7 | 101/2 |
| 8 | 12 |
| 9 | 131/2 |
| 10 | 15 |
| 12 | 18 |
| 14 | 21 |
| 16 | 24 |
| 18 | 27 |
| 20 | 30 |
| 22 | 33 |
| 24 | 36 |
The vent connector shall be routed to the vent utilizing the shortest possible route. Connectors with
longer horizontal lengths than those listed in Table 803.2.1 are permitted under the following conditions:
- The maximum capacity (FAN Max or NAT Max) of the vent connector shall be reduced 10 percent for each additional multiple of the length listed in Table 803.2.1. For example, the maximum length listed for a 4 inch (100 mm) connector is 6 feet (1829 mm) With a connector length greater than 6 feet (1829 mm) but not exceeding 12 feet (3658 mm), the maximum capacity must be reduced by 10 percent (0.90 x maximum vent connector capacity). With a connector length greater than 12 feet (3658 mm) but not exceeding 18 feet (5486 mm), the maximum capacity must be reduced by 20 percent (0.80 x maximum vent capacity).
- For a connector serving a fan-assisted appliance, the minimum capacity (FAN Min) of the connector shall be determined by referring to the corresponding single appliance table. For Type B double-wall connectors, Table 803.1.2(1) shall be used. For single-wall connectors, Table 803.1.2(2) shall be used. The height (H) and lateral (L) shall be measured according to the procedures for a single-appliance vent, as if the other appliances were not present. [NFPA 54:13.2.3]
Where the vent
connectors are combined prior to entering the vertical portion
of the common vent to form a common vent manifold,
the size of the common vent manifold and the common
vent shall be determined by applying a 10 percent reduction
(0.90 x maximum common vent capacity) to the common
vent capacity part of the common vent tables. The length of
the common vent manifold (LM) shall not exceed 18 inches
per inch (18 mm/mm) of common vent diameter (D). (See
Figure 802.6.3.2) [NFPA 54:13.2.4]
Where the common vertical vent
is offset, the maximum capacity of the common vent
shall be reduced in accordance with Section 803.2.5, and
the horizontal length of the common vent offset shall not
exceed 18 inches per inch (18 mm/mm) of common vent
diameter (D). Where multiple offsets occur in a common
vent, the total horizontal length of offsets combined shall
not exceed 18 inches per inch (18 mm/mm) of the common
vent diameter. [NFPA 54:13.2.5]
For each elbow up to and
including 45 degrees (0.79 rad) in the common vent, the
maximum common vent capacity listed in the venting
tables shall be reduced by 5 percent. For each elbow
exceeding 45 degrees (0.79 rad) up to and including 90
degrees (1.57 rad), the maximum common vent capacity
listed in the venting tables shall be reduced by 10 percent.
[NFPA 54:13.2.6]
The vent connector
capacities listed in the common vent sizing tables include
allowance for two 90 degree elbows. For each additional
elbow up to and including 45 degrees, the maximum vent
connector capacity listed in the venting tables shall be
reduced by 5 percent. For each elbow greater than 45
degrees up to and including 90 degrees, the maximum
vent connector capacity listed in the venting tables shall
be reduced by 10 percent.
[NFPA 54:13.2.7]
The cross-sectional
area of the common vent shall be equal to or
greater than the cross-sectional area of the largest connector.
[NFPA 54:13.2.8]
Tee and wye fittings
connected to a common gas vent shall be considered as
part of the common gas vent and constructed of materials
consistent with that of the common gas vent.
[NFPA 54:13.2.9]
At the point where tee or wye
fittings connect to a common gas vent, the opening size
of the fitting shall be equal to the size of the common
vent. Such fittings shall not be prohibited from having
reduced size openings at the point of connection of appliance
gas vent connectors.
[NFPA 54:13.2.10)]
Sea level input
ratings shall be used where determining maximum
capacity for high-altitude installation. Actual input (derated
for altitude) shall be used for determining minimum
capacity for high-altitude installation. [NFPA 54:13.2.11]
The connector rise (R) for each appliance connector shall be measured from the
draft hood outlet or flue collar to the centerline where the
vent gas streams come together.
[NFPA 54:13.2.12]
For multiple appliances located on one floor, the total height (H) shall be measured from
the highest draft hood outlet or flue collar up to the level
of the outlet of the common vent.
[NFPA 54:13.2.13]
For multistory installations, the total height (H) for each segment of the
system shall be the vertical distance between the highest
draft hood outlet or flue collar entering that segment and
the centerline of the next higher interconnection tee. (See
Figure 803.2.13)
[NFPA 54:13.2.14]
FIGURE 803.2.13
MULTISTORY GAS VENT DESIGN PROCEDURE FOR EACH SEGMENT OF SYSTEM
[NFPA 54: FIGURE F.1(m)]
| Multistory gas vent design procedure for each segment of system |
|
| Vent connector size depends on: |
Common vent size depends on: |
| • Input | • Combined imputs |
| • Rise | • Available total height H |
| • Available total height H | • Table 803.2(1) common vent |
| •Table 803.2(1) connectors |
|
MULTISTORY GAS VENT DESIGN PROCEDURE FOR EACH SEGMENT OF SYSTEM
[NFPA 54: FIGURE F.1(m)]
The size of the lowest connector and of the vertical
vent leading to the lowest interconnection of a
multistory system shall be in accordance with Table 803.1.2(1) or Table 803.1.2(2) for available total height
(H) up to the lowest interconnection. (See Figure
803.2.13) [NFPA 54:13.2.15]
FIGURE 803.2.14
PRINCIPLES OF DESIGN OF MULTISTORY VENTS USING VENT CONNECTOR AND COMMON VENT DESIGN TABLES
[NFPA 54: FIGURE F.1(n)]
PRINCIPLES OF DESIGN OF MULTISTORY VENTS USING VENT CONNECTOR AND COMMON VENT DESIGN TABLES
[NFPA 54: FIGURE F.1(n)]
Where
used in multistory systems, vertical common vents shall
be Type B double-wall and shall be installed with a listed
vent cap. [NFPA 54:13.2.16]
Offsets
in multistory common vent systems shall be limited
to a single offset in each system, and systems with an offset
shall comply with the following:
- The offset angle shall not exceed 45 degrees (0.79 rad) from vertical.
- The horizontal length of the offset shall not exceed 18 inches per inch (18 mm/mm) of common vent diameter of the segment in which the offset is located.
- For the segment of the common vertical vent containing the offset, the common vent capacity listed in the common venting tables shall be reduced by 20 percent (0.80 x maximum common vent capacity).
- A multistory common vent shall not be reduced in size above the offset. [NFPA 54:13.2.17]
Where two or more appliances are connected to a vertical vent or chimney,
the flow area of the largest section of vertical vent or
chimney shall not exceed seven times the smallest listed
appliance categorized vent areas, flue collar area, or draft
hood outlet area unless designed in accordance with
approved engineering methods.
[NFPA 54:13.2.18]
For appliances with more than one input rate, the minimum vent connector
capacity (FAN Min) determined from the tables shall be
less than the lowest appliance input rating, and the maximum
vent connector capacity (FAN Max or NAT Max)
determined from the tables shall exceed the highest appliance
input rating. [NFPA 54:13.2.19]
Listed corrugated metallic chimney liner
systems in masonry chimneys shall be sized by using
Table 803.2(1) or Table 803.2(2) for Type B vents, with
the maximum capacity reduced by 20 percent (0.80 x
maximum capacity) and the minimum capacity as shown
in Table 803.2(1) or Table 803.2(2). Corrugated metallic
liner systems installed with bends or offsets shall have
their maximum capacity further reduced in accordance
with Section 803.2.5 and Section 803.2.6. The 20 percent reduction for corrugated metallic chimney liner systems
includes an allowance for one long radius 90 degree
(1.57 rad) turn at the bottom of the liner.
[NFPA 54:13.2.20]
Table 803.2(1) through Table 803.2(5) shall be used only for chimneys and vents not exposed to the outdoors below the roof
line. A Type B vent or listed chimney lining system passing
through an unused masonry chimney flue shall not
be considered to be exposed to the outdoors. A Type B
vent passing through an unventilated enclosure or chase
insulated to a value of not less than R-8 shall not be considered
to be exposed to the outdoors. Where vents
extend outdoors above the roof more than 5 feet (1524
mm) higher than required by Table 802.6.1, and where
vents terminate in accordance with Section 802.6.1(1),
the outdoor portion of the vent shall be enclosed as
required by this section for vents not considered to be
exposed to the outdoors or such venting system shall be
engineered. Table 803.2(6) through Table 803.2(9) shall
be used for clay-tile-lined exterior masonry chimneys,
provided all the following conditions are met:
- The vent connector is Type B double-wall.
- At least one appliance is draft hood-equipped.
- The combined appliance input rating is less than the maximum capacity given by Table 803.2(6) (for NAT+NAT) or Table 803.2(8) (for FAN+NAT).
- The input rating of each space-heating appliance is greater than the minimum input rating given by Table 803.2(7) (for NAT+NAT) or Table 803.2(9) (for FAN+NAT).
- The vent connector sizing is in accordance with Table 803.2(3). [NFPA 54:13.2.22]
Vent connectors
shall not be increased more than two sizes greater than
the listed appliance categorized vent diameter, flue collar
diameter, or draft hood outlet diameter. Vent connectors
for draft hood-equipped appliances shall not be
smaller than the draft hood outlet diameter. Where a vent
connector sizes determined from the tables for a fan-assisted
appliance(s) is smaller than the flue collar diameter,
the use of the smaller size(s) shall be permitted,
provided that the installation complies with all of the following
conditions:
- Vent connectors for fan-assisted appliance flue collars 12 inches (300 mm) in diameter or smaller are not reduced by more than one table size [e.g., 12 inches to 10 inches (300 mm to 250 mm) is a one-size reduction] and those larger than 12 inches (300 mm) in diameter are not reduced more than two table sizes [e.g., 24 inches to 20 inches (600 mm to 500 mm) is a two-size reduction].
- The fan-assisted appliance(s) is common vented with a draft hood-equipped appliance(s).
- The vent connector has a smooth interior wall. [NFPA 54:13.2.24]
All combinations of pipe sizes,
single-wall metal pipe,
and double-wall metal pipe shall be allowed within any
connector run(s) or within the common vent, provided
ALL of the appropriate tables permit ALL of the desired
sizes and types of pipe, as if they were used for the entire
length of the subject connector or vent. Where single-wall
and Type B double-wall metal pipes are used for
vent connectors within the same venting system, the
common vent shall be sized using Table 803.2(2) or
Table 803.2(4) as appropriate. [NFPA 54:13.2.25]
Where a table permits more than one diameter of pipe to
be used for a connector or vent, all the permitted sizes
shall be permitted to be used.
[NFPA 54:13.2.26]
Interpolation shall be permitted
in calculating capacities for vent dimensions that fall
between table entries.
[NFPA 54:13.2.27]
Extrapolation beyond the
table entries shall not be permitted.
[NFPA 54:13.2.28]
For vent heights
lower than 6 feet (1829 mm) and higher than shown in
the tables, engineering methods shall be used to calculate
vent capacities. [NFPA 54:13.2.29]
Where the actual height of a vent falls between entries in the height column of the
applicable table in Table 803.2(1) through Table
803.2(9), one of the following shall be used:
- Interpolation.
- The lower appliance input rating shown in the table entries for FAN MAX and NAT MAX column values; and the higher appliance input rating for the FAN MIN column values. [NFPA 54:13.2.30]
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