CALIFORNIA PLUMBING CODE - MATRIX ADOPTION TABLE
CHAPTER 5 - WATER HEATERS
(Matrix Adoption Tables are non-regulatory, intended only as an aid to the code user. See Chapter 1 for state agency authority and building applications.)
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
2
3
4
Adopt Entire Chapter
X
X
X
X
X
X
X
Adopt Entire Chapter as amended (amended sections listed below)
This state agency does not adopt sections Identified with the following symbol: †
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.
The regulations of this chapter shall
govern the construction, location, and installation of fuel-burning and other types of water heaters heating potable
water, together with chimneys, vents, and their connectors.
The minimum capacity for storage water heaters shall be in
accordance with the first hour rating listed in Table 501.1(1).
No water heater shall be hereinafter installed that does not
comply with the manufacturer's installation instructions and
the type and model of each size thereof approved by the
Authority Having Jurisdiction. A list of accepted water heater
appliancestandards are referenced in Table 501.1(2). Listedappliances shall be installed in accordance with the manufacturer's
installation instructions. Unlisted water heaters
shall be permitted in accordance with Section 504.3.2.
Notes: 1 The first hour rating is found on the "Energy Guide" label. 2 Solar water heaters shall be sized to meet the appropriate first hour rating as shown in the table.
It shall be unlawful for a person to install,
remove, or replace or cause to be installed, removed, or
replaced a water heater without first obtaining a permit from
the Authority Having Jurisdiction to do so.
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.
This inspection shall
be made after work authorized by the permit has been
installed. The Authority Having Jurisdiction will make such
inspection as deemed necessary to be assured that the work
has been installed in accordance with the intent of this code.
No appliance or part thereof shall be covered or concealed
until the same has been inspected and approved by the
Authority Having Jurisdiction.
Water heater installations in bedrooms and
bathrooms shall be in accordance with one of the following
[NFPA 54:10.28.1]:
Fuel-burning water heaters shall be permitted to be
installed in a closet located in the bedroom or bathroom
provided the closet is equipped with a listed, gasketed
door assembly and a listed self-closing device. The self-closing
door assembly shall meet the requirements of
Section 504.1.1. The door assembly shall be installed
with a threshold and bottom door seal and shall meet the
requirements of Section 504.1.2. Combustion air for such
installations shall be obtained from the outdoors in accordance
with Section 506.4. The closet shall be for the
exclusive use of the water heater.
Water heater shall be of the direct vent type. [NFPA
54:10.28.1(2)]
Self-closing doors shall
swing easily and freely, and shall be equipped with a self-closing
device to cause the door to close and latch each
time it is opened. The closing mechanism shall not have
a hold-open feature.
Gasketing on gasketed doors or
frames shall be furnished in accordance with the published
listings of the door, frame, or gasketing material
manufacturer.
Exception: Where acceptable to the Authority Having
Jurisdiction, gasketing of non-combustible or limited-combustible
material shall be permitted to be applied to
the frame, provided closing and latching of the door are
not inhibited.
The clearances shall not
be such as to interfere with combustion air, draft hood
clearance and relief, and accessibility for servicing. Listed
water heaters shall be installed in accordance with their
listings and the manufacturer's installation instructions.
Unlisted water heaters
shall be installed with a clearance of 12 inches (305 mm)
on all sides and rear. Combustible floors under unlisted
water heaters shall be protected in an approved manner.
[NFPA 54:10.28.2.2]
A water heater installation
shall be provided with overpressure protection by means of an
approved, listed device installed in accordance with the terms
of its listing and the manufacturer's installation instructions.
A water heater installation
or a hot water storage vessel installation shall be provided
with overtemperature protection by means of an
approved, listed device installed in accordance with the terms
of its listing and the manufacturer's installation instructions.
Temperature, pressure, and vacuum relief devices
or combinations thereof, and automatic gas shutoff devices,
shall be installed in accordance with the terms of their listings
and the manufacturer's installation instructions. A shutoff valve
shall not be placed between the relief valve and the water heater
or on discharge pipes between such valves and the atmosphere.
The hourly British thermal units (Btu) (kW•h) discharge capacity
or the rated steam relief capacity of the device shall be not
less than the input rating of the water heater.
Water heaters deriving heat from fuels or
types of energy other than gas shall be constructed and installed in accordance with the approvedstandards referenced in Table
501.1(2), Section 505.3, or Section 505.4. Vents or chimneys
for such appliances shall be approved types. An adequate supply
of air for combustion and for adequate ventilation of heater
rooms or compartments shall be provided. Each such appliance
shall be installed in a location approved by the Authority Having
Jurisdiction and local and state fire-prevention agencies.
Storage-type water heaters and hot
water boilers deriving heat from fuels or types of energy other
than gas, shall be provided with, in addition to the primary
temperature controls, an overtemperature safety protection
device constructed, listed, and installed in accordance with
nationally recognized applicable standards for such devices
and a combination temperature and pressure-relief valve.
Indirect-fired water
heaters shall comply with the applicable sections of the ASME
Boiler and Pressure Vessel Code, or to one of the other applicable standards shown in Table 501.1(2). Each water heater
shall bear a label in accordance with ASME requirements, or an
approved testing agency, certifying and attesting that such an
appliance has been tested, inspected and meets the requirements
of the applicable standards or code.
An indirect-fired water heater that incorporates a single-wall heat
exchanger shall be in accordance with the following
requirements:
The heat transfer medium shall be either potable water or contain fluids recognized as safe by the
Food and Drug Administration (FDA) as food grade.
Bear a label with the word "Caution," followed by
the following statements:
The heat-transfer medium shall be potable
water or other nontoxic fluid recognized as safe
by the FDA.
The maximum operating pressure of the heat
exchanger shall not exceed the maximum operating
pressure of the potable water supply.
The word "Caution" and the statements in letters
shall have an uppercase height of not less than 0.120
of an inch (3.048 mm). The vertical spacing between
lines of type shall be not less than 0.046 of an inch
(1.168 mm). Lowercase letters shall be compatible
with the uppercase letter size specification.
Air for combustion, ventilation, and dilution
of flue gases for appliances installed in buildings shall be
obtained by application of one of the methods covered in Section
506.2 through Section 506.7.3. Where the requirements of Section 506.2 are not met, outdoor air shall be introduced
in accordance with methods covered in Section 506.4 through
Section 506.7.3.
Exception: This provision shall not apply to direct-ventappliances. [NFPA 54:9.3.1.1]
Appliances of other
than natural draft design and other than Category I vented
appliances shall be provided with combustion, ventilation,
and dilution air in accordance with the appliance
manufacturer's instructions. [NFPA 54:9.3.1.2]
Where used, a
draft hood or a barometric draft regulator shall be
installed in the same room or enclosure as the appliance
served so as to prevent a difference in pressure between
the hood or regulator and the combustion air supply.
[NFPA 54:9.3.1.4]
Where exhaust fans, clothes dryers,
and kitchen ventilation systems interfere with the
operation of appliances, makeup air shall be provided.
[NFPA 54:9.3.1.5]
The required volume of indoor
air shall be determined in accordance with Section 506.2.1 or
Section 506.2.2, except that where the air infiltration rate is
known to be less than 0.40 ACH (air change per hour), Section
506.2.2 shall be used. The total required volume shall be the
sum of the required volume calculated for appliances located
within the space. Rooms communicating directly with the
space in which the appliances are installed through openings
not furnished with doors, and through combustion air openings
sized and located in accordance with Section 506.3 are
considered a part of the required volume. [NFPA 54:9.3.2]
Openings used
to connect indoor spaces shall be sized and located in accordance
with the following:
Each opening shall have a free area of not less than 1
square inch per 1000 Btu/h (0.002 m2/kW) of the total
input rating of appliances in the space, but not less than
100 square inches (0.065 m2). One opening shall commence
within 12 inches (305 mm) of the top of the enclosure
and one opening shall commence within 12 inches
(305 mm) of the bottom of the enclosure (see Figure
506.3). The dimension of air openings shall be not less
than 3 inches (76 mm).
The volumes of spaces in different stories shall be considered
as communicating spaces where such spaces are
connected by one or more openings in doors or floors
having a total free area of not less than 2 square inches
per 1000 Btu/h (0.004 m2/kW) of total input rating of
appliances. [NFPA 54:9.3.2.3]
FIGURE 506.3
COMBUSTION AIR FROM ADJACENT INDOOR SPACES
THROUGH INDOOR COMBUSTION AIR OPENINGS
[NFPA 54: FIGURE A.9.3.2.3(1)]
Outdoor combustion air shall
be provided through opening(s) to the outdoors in accordance
with methods in Section 506.4.1 or Section 506.4.2. The dimension
of air openings shall be not less than 3 inches (76 mm).
[NFPA 54:9.3.3]
Two permanent openings, one commencing within 12 inches (305 mm) of the top of the enclosure and one commencing within 12 inches (305 mm) of the bottom of the enclosure shall be provided. The openings shall communicate directly, or by ducts, with the outdoors or spaces that freely communicate with the outdoors as follows:
Where directly communicating with the outdoors or
where communicating to the outdoors through vertical
ducts, each opening shall have a free area of not
less than 1 square inch per 4000 Btu/h (0.0005
m2/kW) of total input rating of appliances in the
enclosure. [See Figure 506.4(1) and Figure 506.4(2)]
Where communicating with the outdoors through
horizontal ducts, each opening shall have a free area
of not less than 1 square inch per 2000 Btu/h (0.001
m2/kW) of total input rating of appliances in the
enclosure. [See Figure 506.4(3)] [NFPA 54:9.3.3.1]
FIGURE 506.4(1)
COMBUSTION AIR FROM OUTDOORS
INLET AIR FROM VENTILATED CRAWL SPACE AND
OUTLET AIR TO VENTILATED ATTIC
[NFPA 54: FIGURE A.9.3.3.1(1)(a)]
For SI units: 1 foot = 304.8 mm
FIGURE 506.4(2)
COMBUSTION AIR FROM OUTDOORS
THROUGH VENTILATED ATTIC
[NFPA 54: FIGURE A.9.3.3.1(1)(b)] FIGURE 506.4(3)
COMBUSTION AIR FROM
OUTDOORS THROUGH HORIZONTAL DUCTS
[NFPA 54: FIGURE A.9.3.3.1(2)]
One permanent
opening, commencing within 12 inches (305 mm) of
the top of the enclosure, shall be provided. The appliance
shall have clearances of not less than 1 inch (25.4 mm)
from the sides and back and 6 inches (152 mm) from the
front of the appliance. The opening shall directly communicate
with the outdoors or shall communicate through a
vertical or horizontal duct to the outdoors or spaces that
freely communicate with the outdoors (see Figure 506.4.2)
and shall have a free area not less than the following:
One square inch per 3000 Btu/h (0.0007 m2/kW) of
the total input rating of appliances located in the
enclosure.
Not less than the sum of the areas of vent connectors
in the space. [NFPA 54:9.3.3.2]
FIGURE 506.4.2
COMBUSTION AIR FROM OUTDOORS THROUGH
SINGLE COMBUSTION AIR OPENING
[NFPA 54: FIGURE A.9.3.3.2]
The use of a combination of indoor and outdoor combustion air
shall be in accordance with Section 506.5.1 through Section
506.5.3 (see calculation example in Appendix J). [NFPA
54:9.3.4]
The outdoor opening(s) size shall be calculated in accordance with the following:
The ratio of interior spaces shall be the volume of
the communicating spaces divided by the required
volume.
The outdoor size reduction factor shall be one minus
the ratio of interior spaces.
The size of outdoor openings shall be not less than
the full size of outdoor openings calculated in accordance
with Section 506.4, multiplied by the reduction
factor. The dimension of air openings shall be
not less than 3 inches (76 mm). [NFPA 54:9.3.4(3)]
Engineered combustion air
installations shall provide a supply of combustion, ventilation,
and dilution air that is approved by the Authority Having
Jurisdiction. [NFPA 54:9.3.5]
Where combustion
air is provided by a mechanical air supply system, the
combustion air shall be supplied from outdoors at the minimum rate of 0.35 cubic feet per minute per 1000 Btu/h [0.034 (m3/min)/kW] for appliances located within the space. [NFPA 54:9.3.6]
Each of the appliances served shall
be interlocked to the mechanical air supply system to prevent
main burner operation where the mechanical air
supply system is not in operation. [NFPA 54:9.3.6.2]
Where combustion
air is provided by the building's mechanical ventilation
system, the system shall provide the specified combustion
air rate in addition to the required ventilation air.
[NFPA 54:9.3.6.3]
The required size of
openings for combustion, ventilation, and dilution air shall
be based on the net free area of each opening. Where the free area through a design of louver, grille, or screen is known, it
shall be used in calculating the size opening required to provide the free area specified. Where the louver and grille
design and free area are not known, it shall be assumed that
wood louvers have 25 percent free area and metal louvers and
grilles have 75 percent free area. Nonmotorized louvers and
grilles shall be fixed in the open position. [NFPA 54:9.3.7.1]
Motorized louvers shall be
interlocked with the appliance so they are proven in the
full open position prior to main burner ignition and during
main burner operation. Means shall be provided to
prevent the main burner from igniting where the louver
fail to open during burner start-up and to shut down the
main burner where the louvers close during burner operation.
[NFPA 54:9.3.7.3]
Combustion air ducts shall
comply with the following [NFPA 54:9.3.8]:
Ducts shall be constructed of galvanized steel or a material having equivalent corrosion resistance, strength, and
rigidity.
Exception: Within dwelling units, unobstructed stud and
joist spaces shall not be prohibited from conveying combustion
air, provided that not more than one fireblock is
removed. [NFPA 54:9.3.8.1]
Ducts shall terminate in an unobstructed space, allowing
free movement of combustion air to the appliances.
[NFPA 54:9.3.8.2]
Ducts shall serve a single space. [NFPA 54:9.3.8.3]
Ducts shall not service both upper and lower combustion
air openings where both such openings are used. The separation
between ducts serving upper and lower combustion
air openings shall be maintained to the source of
combustion air. [NFPA 54:9.3.8.4]
Ducts shall not be screened where terminating in an attic
space. [NFPA 54:9.3.8.5]
Combustion air intake openings located on the exterior of
the building shall have the lowest side of the combustion
air intake openings located not less than 12 inches (305
mm) vertically from the adjoining finished ground level.
[NFPA 54:9.3.8.8]
Horizontal upper combustion air ducts shall not slope
downward toward the source of combustion air. [NFPA
54:9.3.8.6]
The remaining space surrounding a chimney liner, gas
vent, special gas vent, or plastic piping installed within a
masonry, metal, or factory-built chimney 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 54:9.3.8.7]
The Authority Having Jurisdiction
shall have the authority to require the use of an approved
dielectric insulator on the water piping connections of water
heaters and related water heating appliances.
Water heaters shall be anchored or strapped to resist horizontal displacement due to earthquake
motion. Strapping shall be at points within the upper one third (1/3) and lower one-third (1/3) of its vertical dimensions.
At the lower point, a minimum distance of four (4)
inches (102 mm) shall be maintained above the controls with
the strapping.
Note:[HCD 1 & HCD 2] Reference Health and Safety Code
Section 19211(a) which addresses new, replacement, and
existing water heaters.
Note: The applicable subsection of Health and Safety Code Section
19211(a) which addresses new, replacement, and existing
water heaters is repeated here for clarity and reads as follows:
Section 19211(a) Notwithstanding Section 19100, all new
and replacement water heaters, and all existing residential
water heaters shall be braced, anchored, or strapped to resist
falling or horizontal displacement due to earthquake motion.
At a minimum, any water heater shall be secured in accordance
with the California Plumbing Code, or modifications
made thereto by a city, county, or city and county pursuant to
Section 17958.5.
Appliances and equipment
shall be furnished either with load-distributing bases or with
an approved number of supports to prevent damage to either the building structure or the appliance and the equipment.
[NFPA 54:9.1.8.1]
At the locations selected for installation of appliances and equipment, the
dynamic and static load-carrying capacities of the building structure shall be checked to determine whether they are capable to carry the additional loads, Appliances and equipment shall be supported and shall be connected to the piping so as not to exert undue stress on the connections.
[NFPA 54:9.1.8.2]
A water heater supported from the
ground shall rest on level concrete or other approved base
extending not less than 3 inches (76 mm) above the adjoining
ground level.
Where a water heater is located in an attic. in or on an attic-ceiling assembly, floor-ceiling assembly, or floor-subfloor assembly where damage results from a leaking water heater, a watertight pan of corrosion-resistant materials shall be installed beneath the water heater with not less than 3/4 of an inch (20 mm) diameterdrain to an approved location. Such pan shall be not less than 11/2 inches (38 mm) in depth.
Where additional or replacement equipment or appliances are
installed or an appliance is converted to gas from another fuel, the location in which the equipment or appliance is to be operated
shall be checked to verify the following:
Air for combustion and ventilation is provided where
required, in accordance with the provisions of Section
506.0. Where existing facilities are not adequate, they
shall be upgraded to be in accordance with Section 506.0
specifications, [NFPA 54:9.1.2(1)]
The installation components and appliances shall be installed with clearances to combustible material so their
operation will not create a hazard to persons or property.
Minimum clearances between combustible walls and the
back and sides of various conventional types of appliances and their vent connectors are specified in Table
509.7.3(1) and Table 509.7.3(2). [NFPA 54:9.2.2] It shall
be determined that the installation and operation of the
additional or replacement appliances do not render the remaining appliances unsafe for continued operation.
The venting system is constructed and sized in accordance
with the provisions of Section 509.0. Where the existing venting system is not adequate, it shall be upgraded in
accordance with Section 509.0. [NFPA 54:9.1.2(3)]
The appliance shall be connected to
the fuel gas for which it was designed. No attempt shall be
made to convert the appliance from the gas specified on the
rating plate for use with a different gas without consulting the
installation instructions, the serving gas supplier, or the appliance
manufacturer for complete instructions. [NFPA 54:9.1.3]
Unlisted appliances for use with undiluted
liquefied petroleum gases and installed indoors, except attended laboratory equipment, shall be equipped with safety
shutoff devices of the complete shutoff type. [NFPA 54:9.1.4]
Where air or
oxygen under pressure is used in connection with the gas supply,
effective means such as a backpressure regulator and
relief valve shall be provided to prevent air or oxygen from
passing back into the gas piping. Where oxygen is used, installation shall be in accordance with NFPA 51. [NFPA
54:9.1.5]
Nondirect-ventappliances installed in beauty shops, barber shops, or other facilities where chemicals that generate corrosive or
flammable products such as aerosol sprays are routinely used
shall be located in a mechanical equipment room separate or partitioned off from other areas with provisions for combustion
and dilution air from outdoors. Direct-vent appliances in such facilities shall be installed in accordance with the appliance manufacturer's installation instructions. [NFPA 54:9.1.6.2]
In addition to air needed for combustion
in commercial or industrial processes, process air shall be provided
as required for cooling of appliances, equipment, or material; for controlling dew point, heating, drying, oxidation,
dilution, safety exhaust, odor control, air for compressors;
and for comfort and proper working conditions for
personnel. [NFPA 54:9.1.7]
Appliances shall not be installed in areas where the open use, handling, or dispensing
of flammable liquids occurs, unless the design, operation, or
installation reduces the potential of ignition of the flammable
vapors. Appliances installed in accordance with Section
507.13, Section 507.14, or Section 507.15 shall be considered
to be in accordance with the intent of this provision.
[NFPA 54:9.1.9]
Appliances in garages and in
adjacent spaces that open to the garage and are not part of the
living space of a dwelling unit shall be installed so that burners
and burner-ignition devices are located not less than 18
inches (457 mm) above the floor unless listed as flammable
vapor ignition resistant. [NFPA 54:9.1.10.1]
Appliances installed in
garages, warehouses, or other areas subject to mechanical
damage shall be guarded against such damage by being
installed behind protective barriers or by being elevated or
located out of the normal path of vehicles.
Where appliances
are installed within a garage and are enclosed in a
separate enclosed space having access only from outside
of the garage, such appliances shall be permitted to be
installed at floor level, provided the required combustion
air is taken from the exterior of the garage. [NFPA
54:9.1.10.3]
Appliances installed in repair
garages shall be installed in a detached building or room,
separated from repair areas by walls or partitions, floors,
or floor-ceiling assemblies that are constructed so as to
prohibit the transmission of vapors and having a fire-resistance
rating of not less than 1 hour, and that have no openings
in the wall separating the repair area within 8 feet
(2438 mm) of the floor. Wall penetrations shall be
firestopped. Air for combustion purposes shall be obtained
from outside the building. The heating room shall not be
used for the storage of combustible materials.
Exceptions:
Overhead heaters where installed not less than 8 feet
(2438 mm) above the floor shall be permitted.
Heating appliances for vehicle repair areas where
there is no dispensing or transferring of Class I or
Class II flammable or combustible liquids or liquefied
petroleum gas shall be installed in accordance
with NFPA 30A. [NFPA 54:9.1.11.2]
Where additional
appliances are being connected to a gas piping system, the
existing piping shall be checked to determine where it has
adequate capacity. Where inadequate, the existing system
shall be enlarged as necessary, or separate gas piping of adequate
capacity shall be run from the point of delivery to the
appliance. [NFPA 54:9.1.16]
Where the gas
supply pressure is higher than that at which the appliance is
designed to operate or varies beyond the design pressure limits
of the appliance, a gas appliancepressure regulator shall be
installed. [NFPA 54:9.1.18]
Venting of gas appliancepressure regulators shall be in accordance
with the following requirements:
Appliancepressure regulators requiring access to the atmosphere for successful operation shall be equipped
with vent piping leading outdoors or, where the regulator
vent is an integral part of the appliance, into the combustion
chamber adjacent to a continuous pilot, unless
constructed or equipped with a vent limiting means to
limit the escape of gas from the vent opening in the event
of diaphragm failure.
In the case of vents leading outdoors, means shall be
employed to prevent water from entering this piping and
also to prevent blockage of vents by insects and foreign
matter.
Under no circumstances shall a regulator be vented to the
appliance flue or exhaust system.
In the case of vents entering the combustion chamber,
the vent shall be located so the escaping gas will be readily
ignited by the pilot and the heat liberated thereby will
not adversely affect the normal operation of the safety
shutoff system. The terminus of the vent shall be securely
held in a fixed position relative to the pilot. For manufactured
gas, the need for a flame arrester in the vent piping
shall be determined.
Vent lines from an appliancepressure regulator and bleed lines from a diaphragm-type valve shall not be connected
to a common manifold terminating in a combustion chamber.
Vent lines shall not terminate in positive-pressure-type
combustion chambers. [NFPA 54:9.1.19]
Bleed lines
shall comply with the following requirements:
Diaphragm-type valves shall be equipped to convey
bleed gas to the outdoors or into the combustion chamber
adjacent to a continuous pilot.
In the case of bleed lines leading outdoors, means shall
be employed to prevent water from entering this piping
and also to prevent blockage of vents by insects and foreign
matter.
Bleed lines shall not terminate in the appliance flue or
exhaust system.
In the case of bleed lines entering the combustion chamber,
the bleed line shall be located so the bleed gas will
be readily ignited by the pilot and the heat liberated
thereby will not adversely affect the normal operation of
the safety shutoff system. The terminus of the bleed line
shall be securely held in a fixed position relative to the
pilot. For manufactured gas, the need for a flame arrester
in the bleed line piping shall be determined.
Bleed lines from a diaphragm-type valve and vent lines
from an appliancepressure regulator shall not be connected to a common manifold terminating in a combustion
chamber. Bleed lines shall not terminate in positive-pressure-type combustion chambers. [NFPA 54:9.1.20]
A combination of appliances, equipment, attachments, or
devices used together in a manner shall be in accordance with the standards that apply to the individual appliance and equipment.
[NFPA 54:9.1.21]
The installing agency shall comply with the appliance and equipment manufacturer's
installation instructions in completing an installation. The installing agency shall leave the manufacturer's installation,
operating, and maintenance instructions in a location on the
premises where they will be readily available for reference and
guidance for the Authority Having Jurisdiction, service personnel,
and the owner or operator. [NFPA 54:9.1.22]
Appliances not
listed for outdoor installation but installed outdoors shall be
provided with protection to the degree that the environment
requires. Applianceslisted for outdoor installation shall be
permitted to be installed without protection in accordance with the provisions of its listing and the manufacturer's installation instructions.
Appliances shall be located
with respect to building construction and other equipment so as
to permit access to the appliance. Sufficient clearance shall be
maintained to permit cleaning of heating surfaces; the replacement
of filters, blowers, motors, burners, controls, and vent
connections; the lubrication of moving parts where necessary;
the adjustment and cleaning of burners and pilots; and the
proper functioning of explosion vents, where provided. For
attic installation, the passageway and servicing area adjacent
to the appliance shall be floored. [NFPA 54:9.2.1]
Equipment and appliances on roofs shall be
designed or enclosed so as to withstand climatic conditions in
the area in which they are installed. Where enclosures are provided,
each enclosure shall permit easy entry and movement,
shall be of reasonable height, and shall have not less than a 30
inch (762 mm) clearance between the entire service access panel(s) of the equipment and appliance and the wall of the
enclosure. [NFPA 54:9.4.1.1]
Roofs on which equipment
and appliances are to be installed shall be capable of supporting
the additional load or shall be reinforced to support
the additional load. [NFPA 54:9.4.1.2]
Equipment and appliances shall be
installed on a well-drained surface of the roof. Not less
than 6 feet (1829 mm) of clearance shall be between a
part of the equipment and appliance and the edge of a roof or similar hazard, or rigidly fixed rails, guards, parapets,
or other building structures not less than 42 inches
(1067 mm) in height shall be provided on the exposed
side. [NFPA 54:9.4.2.2]
Equipment and appliances requiring an external source of electrical power for its
operation shall be provided with the following:
A readily accessible electrical disconnecting means
within sight of the equipment and appliance that will completely de-energize the equipment and appliance.
A 120-VAC grounding-type receptacle outlet on the
roof adjacent to the equipment and appliance. The receptacle outlet shall be on the supply side of the
disconnect switch. [NFPA 54:9.4.2.3]
Where water stands on
the roof at the equipment and appliance or in the passageways to the equipment and appliance, or where the roof is of a design having a water seal, an approved platform, walkway, or both shall be provided above the waterline. Such platforms or walkways shall be located adjacent to the equipment and appliance and control panels so that the equipment and appliance is capable of being safely serviced where water stands on the roof. [NFPA 54:9.4.2.4]
Buildings exceeding 15 feet (4572 mm)
in height shall have an inside means of access to the roof,
unless other means acceptable to the Authority Having
Jurisdiction are used. [NFPA 54:9.4.3.2]
The inside means of access shall be
a permanent, or fold-away inside stairway or ladder, terminating
in an enclosure, scuttle, or trap door. Such scuttles
or trap doors shall be not less than 22 inches by 24
inches (559 mm by 610 mm) in size, shall open easily and
safely under all conditions, especially snow; and shall be
constructed so as to permit access from the roof side
unless deliberately locked on the inside.
Not less than 6 feet (1829 mm) of clearance shall be
between the access opening and the edge of the roof or
similar hazard, or rigidly fixed rails or guards not less than
42 inches (1067 mm) in height shall be provided on the
exposed side. Where parapets or other building structures
are utilized in lieu of guards or rails, they shall be not less than 42 inches (l067 mm) in height. [NFPA 54:9.4.3.3]
Permanent lighting shall be provided at the roof access. The switch for such lighting shall be located inside the building near the access means leading to the roof. [NFPA 54:9.4.3.4]
An attic or under-floor space in which an appliance is installed shall be accessible through an opening and passageway not less than as large as the largest component of the appliance, and not less than 22 inches by 30 inches (559 mm by 762 mm).
Where the height of the
passageway is less than 6 feet (1829 mm), the distance
from the passageway access to the appliance shall not exceed 20 feet (6096 mm) measured along the centerline
of the passageway. [NFPA 54:9.5.1.1]
The passageway shall be
unobstructed and shall have solid flooring not less than
24 inches (610 mm) wide from the entrance opening to
the appliance. [NFPA 54:9.5.1.2]
A level working platform not
less than 30 inches by 30 inches (762 mm by 762 mm)
shall be provided in front of the service side of the appliance.
[NFPA 54:9.5.2]
A permanent
120-volt receptacle outlet and a lighting fixture shall
be installed near the appliance. The switch controlling
the lighting fixture shall be located at the entrance to the
passageway. [NFPA 54:9.5.3]
The following appliances shall not be required to be vented [NFPA 54:12.3.2]:
A single listed booster-type (automatic instantaneous)
water heater, where 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 where a
draft hood is required, in a commercial kitchen having
a mechanical exhaust system; where installed in
this manner, the draft hood outlet shall be not less
than 36 inches (914 mm) vertically and 6 inches
(152 mm) horizontally from a surface other than the
appliance. [NFPA 54:12.3.2(5)]
Where appliances in Section 509.2.1(1) and Section
509.2.1(2) are installed so the aggregate input rating
exceeds 20 British thermal units per hour per cubic foot
[(Btu/h)/ft3] (0.21 kW/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 appliance does not exceed 20
[(Btu/h)/ft3] (0.21 kW/m3). Where the calculation includes
the volume of an adjacent room or space, the room or
space in which the appliance is 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 54:12.3.2.1, 12.3.2.2]
Ventilating hoods and
exhaust systems shall be permitted to be used to ventappliances 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]
Appliances incorporating integral venting means shall be installed in accordance with the manufacturer's installation instructions, Section 509.8, and Section 509.8.1. [NFPA 54:12.3.6]
Appliances required to be vented shall be connected to a venting system designed and installed in accordance with the provisions of Section 509.4 through Section 509.14 of this
code. [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 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 509.8 and Section 509.8.1 of this code. [NFPA 54:12.4.3.6]
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]
Plastic pipe and fittings used
to ventappliances 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]
Factory-built chimneys
shall comply with the requirements of UL 103 or
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]
Masonry chimneys shall
be built and installed in accordance with NFPA 211 and
lined with approved clay flue lining, a listedchimney 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 listedappliances with draft hoods, Category I appliances, and other
applianceslisted 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 tor 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 the 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 509.5.4) [NFPA 54:12.6.2.1]
For SI units: 1 foot = 304.8 mm
FIGURE 509.5.4
TYPICAL TERMINATION LOCATIONS FOR CHIMNEYS
AND SINGLE-WALL METAL PIPES SERVING
RESIDENTIAL-TYPE AND LOW-HEAT APPLIANCE
[NFPA 54: FIGURE A.12.602.1]
A chimney
for a medium-heat appliance shall extend not less than
10 feet (3048 mm) above a portion of a building within
25 feet (7620 mm). [NFPA 54:12.6.2.2]
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 listedappliances with draft hoods, Category I appliances, and other applianceslisted for use with Type B vents shall be in accordance with one of the following methods [NFPA 54:12.6.3.1]:
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 applianceflue collar
or draft hood outlet or exceeding seven times the
draft hood outlet area. [NFPA 54:12.6.3.1(2)]
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 exceeding
seven times the smallest draft hood outlet area.
[NFPA 54:12.6.3.1(3)]
Other approved engineering methods. [NFPA 54:12.6.3.1(5)]
Chimney venting systems using mechanical draft
shall be sized in accordance with approved engineering
methods. [NFPA 54:12.6.3.1(4)]
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 where an appliance is
replaced by an appliance of similar type, input rating,
and efficiency, where the chimney is in accordance
with Section 509.5.6, and the sizing of the
chimney is in accordance with Section 509.5.5.
[NFPA 54:12.6.4.2]
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]
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]
Portions of chimneys
shall be supported for the design and weight of the materials
employed. Listedfactory-built chimneys shall be
supported and spaced in accordance with the manufacturer's
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]
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(4)]
A gas vent shall terminate in accordance with one of the following:
Gas vents that are 12 inches (305 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 509.6.2 and Table
509.6.2. Gas vents that are over 12 inches (305 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.
Mechanical draft systems as provided in Section
509.3.3.
Ventilating hoods and exhaust systems as provided
in Section 509.3.4. [NFPA 54:12.7.2(1)]
FIGURE 509.6.2
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]
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 gas vent
extending through an exterior wall shall not terminate
adjacent to the wall or below eaves or parapets,
except as provided in Section 509.2.4 and Section
509.3.3. [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 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)]
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 510.0
or other approved engineering methods and the gas vent
and gas appliance manufacturer's instructions. [NFPA 54:12.7.3]
The sizing of
natural draft venting systems serving one or more
listedappliances equipped with a draft hood or
applianceslisted for use with Type B gas vent,
installed in a single story of a building, shall be in
accordance with one of the following:
Vents serving fan-assisted combustion system
appliances, or combinations of fan-assisted
combustion systems and draft hood-equipped
appliances, shall be sized in accordance with
Section 510.0 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.
Type B or Type L vents shall extend in a vertical direction with offsets not exceeding
45 degrees (0.79 rad), except that a vent system
having not more than one 60 degree (1.05 rad) offset
shall be permitted. An angle greater than 45
degrees (0.79 rad) from the vertical is considered
horizontal. The total horizontal distance of a vent
plus the horizontal vent connector serving draft
hood-equipped appliances shall be not greater than
75 percent of the vertical height of the vent. [NFPA 54:12.7.3.2]
A commonvent 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]
Appliances connected
to the commonvent 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
509.6.4.1) [NFPA 54:12.7.4.2]
FIGURE 509.6.4.1
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 applianceslisted for use
with a Type B double-wall gas vent shall be in accordance
with Table 510.2(1), provided the following
apply:
The 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
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, shall be based on the total appliance's gas input rate entering that segment and its total height. [NFPA 54:12.7.4.3]
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
bum 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. 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 comply with the following requirements:
Single-wall metal pipe shall terminate not less than 5
feet (1524 mm) in vertical height above the highest
connected appliance draft hood outlet or flue collar.
Single-wall metal pipe shall extend not less than 2
feet (610 mm) above the highest point where it
passes through the roof of a building and not less
than 2 feet (610 mm) exceeding a portion ofa building
within a horizontal distance of 10 feet (3048
mm). (See Figure 509.5.4)
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]
Notes:
1 A - Equals the clearance with no protection specified in Table 509.7.3(1)
and Table 509.7.3(2) and in the sections applying to various types of appliances.
2 B - Equals the reduced clearance permitted in accordance with Table
509.7.3(2)
3 The protection applied to the construction using combustible material
shall extend far enough in each direction to make C equal to A.
FIGURE 509.7.3(1)1, 2, 3
EXTENT OF PROTECTION NECESSARY TO REDUCE CLEARANCES
FROM GAS APPLIANCES OR VENT CONNECTORS
[NFPA 54: FIGURE 10.3.2.3(a)]For SI units: 1 inch = 25.4 mm Note: Masonry walls shall be attached to combustible walls using wall ties.
Spacers shall not be used directly behind appliance or connector.FIGURE 509.7.3(2)
WALL PROTECTION REDUCTION SYSTEM
[NFPA 54: FIGURE 10.3.2.3(b)] For SI units: 1 inch = 25.4 mmFIGURE 509.7.3(3)
MASONRY CLEARANCE REDUCTION SYSTEM
[NFPA 54: FIGURE 10.3.2.3(c)]
TABLE 509.7.3(1)
CLEARANCE FOR CONNECTORS
[NFPA 54: TABLE 12.8.4.4]*
* These clearances shall apply unless the installation instructions of a listedappliance or connector specify different clearances, in which case the listed clearances
shall apply.
TABLE 509.7.3(2)
REDUCTION OF CLEARANCES WITH SPECIFIED FORMS OF PROTECTION1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11
[NFPA 54: TABLE 10.2.3]
TYPE OF PROTECTION APPLIED TO AND COVERING SURFACES OF COMBUSTIBLE MATERIAL WITHIN THE DISTANCE SPECIFIED AS THE REQUIRED CLEARANCE WITH NO PROTECTION [SEE FIGURE 509.7.3(1) THROUGH FIGURE 509.7.3(3)]
WHERE THE REQUIRED CLEARANCE WITH NO PROTECTION FROM APPLIANCE, VENT CONNECTOR, OR SINGLE-WALL METAL PIPE IS:
36 (inches)
18 (inches)
12 (inches)
9 (inches)
6 (inches)
ALLOWABLE CLEARANCES WITH SPECIFIED PROTECTION (inches)
USE COLUMN 1 FOR CLEARANCES ABOVE APPLIANCE OR HORIZONTAL CONNECTOR. USE COLUMN 2 FOR CLEARANCES FROM APPLIANCES, VERTICAL CONNECTOR, AND SINGLE-WALL METAL PIPE.
ABOVE COLUMN 1
SIDES AND REAR COLUMN 2
ABOVE COLUMN 1
SIDES AND REAR COLUMN 2
ABOVE COLUMN 1
SIDES AND REAR COLUMN 2
ABOVE COLUMN 1
SIDES AND REAR COLUMN 2
ABOVE COLUMN 1
SIDES AND REAR COLUMN 2
(1) 31/2 inch thick masonry wall without ventilated air space
-
24
-
12
-
9
-
6
-
5
(2) 1/2 of an inch insulation board over 1 inch glass fiber or mineral woll batts
24
18
12
9
9
6
6
5
4
3
(3) 0.024 inch sheet metal over 1 inch glass fiber or mineral woll batts reinforced with wire on rear face with ventilated air space
18
12
9
6
6
4
5
3
3
3
(4) 31/2 inch thick masonry wall with ventilated air space
-
12
-
6
-
6
-
6
-
6
(5) 0.024 inch sheet metal with ventilated air space
18
12
9
6
6
4
5
3
3
2
(6) 1/2 of an inch thick insulation board with ventilated air space
18
12
9
6
6
4
5
3
3
3
(7) 0.024 inch sheet metal with ventilated air space over 0.024 inch sheet metal with ventilated air space
18
12
9
6
6
4
5
3
3
3
(8) 1 inch glass fiber or mineral wool
batts sandwiched between two sheets 0.024 inch sheet metal with ventilated air space
18
12
9
6
6
4
5
3
3
3
For SI units: 1 inch = 25.4 mm, °C = (°F-32)/1.8
Notes:
1 Reduction of clearances from combustible materials shall not interfere with combustion air, draft hood clearance and relief, and accessibility of servicing.
2 Clearances shall be measured from the outer surface of the combustible material to the nearest point on the surface of the appliance, disregarding an intervening
protection applied to the combustible material.
3 Spacers and ties shall be of noncombustible material. No spacer or tie shall be used directly opposite the appliance or connector.
4 Where clearance reduction systems use a ventilated air space, adequate provision for air circulation shall be provided as described. [See Figure 509.7.3(2)
and Figure 509.7.3(3)]
5 There shall be not less than 1 inch (25.4 mm) between clearance reduction systems and combustible walls and ceilings for reduction systems using a ventilated
air space.
6 Where a wall protector is mounted on a single flat wall away from comers, it shall have a minimum 1 inch (25.4 mm) air gap. To provide air circulation,
the bottom and top edges, or only the side and top edges, or edges shall be left open.
7 Mineral wool batts (blanket or board) shall have a minimum density of 8 pounds per cubic foot (lb/ft3) (128 kg/m3) and a minimum melting point of 1500°F
(816°C).
8 Insulation material used as part of a clearance reduction system shall have a thermal conductivity of 1 British thermal unit inch per hour square foot degree
Fahrenheit [Btu•in/(h•ft2•°F)] [0.1 W/(m•K)) or less.
9 There shall be not less than 1 inch (25.4 mm) between the appliance and the protector. In no case shall the clearance between the appliance and the combustible
surface be reduced below that allowed in this table.
10 Clearances and thicknesses are minimum; larger clearances and thicknesses are acceptable.
11Listed single-wall connectors shall be installed in accordance with the terms of their listing and the manufacturer's installation instructions.
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]
Single-wall metal pipe used
for venting an incinerator shall be exposed and readily
examinable for its full length and shall have
required clearances maintained.
Minimum clearances from
single-wall metal pipe to combustible material shall
be in accordance with Table 509.7.3(1). Reduced
clearances from single-wall metal pipe to combustible
material shall be as specified for vent connectors
in Table 509.7.3(2). [NFPA 54:12.8.4.4]
A 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 listedappliances with draft hoods and applianceslisted for use with Type B gas vents, the
thimble shall be not less than 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 not less than 2 inches (51 mm) larger in
diameter than the metal pipe.
For unlisted appliances having draft hoods, the
thimble shall be not less than 6 inches (152 mm)
larger in diameter than the metal pipe.
For residential and low-heat appliances, the
thimble shall be not less than 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 from the metal pipe to provide the specified clearance from combustible material. 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 509.7.3.5. [NFPA 54:12.8.4.5]
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 venting system for a single appliance with
a draft hood, the areas of the connector and the
pipe each shall be not less than the area of the
applianceflue 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)]
(See Figure
509.8) A mechanical draft venting system shall terminate not
less than 3 feet (914 mm) above a forced air inlet located
within 10 feet (3048 mm).
Exceptions:
This provision shall not apply to the combustion air
intake of a direct-ventappliance.
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]
FIGURE 509.8
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-ventappliance with an input of 10000 Btu/h (3 kW)
or less shall be located not less than 6 inches (152 mm)
from an air opening into a building, and such an appliance
with an input exceeding 10000 Btu/h (3 kW) but not
exceeding 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 not less than a 12 inch (305 mm) vent termination clearance. The bottom of the vent terminal and the air
intake shall be located not less than 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 is capable of creating a nuisance or hazard 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]
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 terminals 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 509.8.3.
[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 509.8.3. [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 listedvent 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 listedappliances 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:
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 exceeding
that of Section 509.10.1.2(1)(b). Section
509.10.1.2(1)(c), or Section 509.10.1.2(1)(d)
above.
A vent connector for a non-residential low-heat appliance shall be a factory-built chimney section or steel pipe having resistance to heat and corrosion equivalent to the galvanized pipe specified in Table 509.10.1.3. Factory-built chimney sections shall be installed in accordance with the chimney manufacturer's installation instructions. [NFPA 54:12.11.2.4]
Vent connectors
for medium-heat appliances, and commercial and
industrial incinerators, shall be constructed of factory-built,
medium-heat chimney sections or steel of a
thickness not less than that specified in Table
509.10.1.4 and shall comply with the following:
A steel vent connector for appliances 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 not less than 21&fral;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 not less than 41&fral;2 inches (114
mm) thick laid on the 41&fral;2 inch (114 mm) bed for
a vent connector having a diameter or cross-sectional
dimension exceeding 18 inches (457 mm).
Factory-built chimney sections, where employed,
shall be installed in accordance with the chimney
manufacturer's installation instructions. [NFPA
54:12.11.2.5]
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 510.0 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 alternate
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 not
less than 1 foot (305 mm) rise. [NFPA 54:12.11.3.2]
Where two or more appliances are
connected to a commonvent or chimney, each vent
connector shall be sized in accordance with Section
510.0 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]
Where two or more appliances
are vented through a commonvent connector or vent
manifold, the commonvent connector or vent manifold
shall be located at the highest level consistent
with available headroom and clearance to combustible
material and shall be sized in accordance
with Section 510.0 or other approved engineering
methods. [NFPA 54:12.11.3.5]
As an alternate method applicable where there
are two draft hood-equipped appliances, the effective
area of the commonvent connector or vent manifold
and junction fittings shall be not less than the
area of the larger vent connector plus 50 percent of
the areas of smaller flue collar outlets. [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 Hue or vent, the openings shall be at different levels, or the connectors shall be attached to the
vertical portion of the chimney or vent at an angle of 45
degrees (0.79 rad) or less relative to the vertical. [NFPA
54:12.11.4.1]
Where two or
more vent connectors enter a commonvent, 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]
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:
By sheet metal screws.
Vent connectors of listedvent material shall be
assembled and connected to flue collars or draft
hood outlets in accordance with the manufacturer's
installation instructions.
A vent connector shall be installed without
dips or sags and shall slope upward toward the vent or
chimney not less than 1/4 inch per foot (20.8 mm/m).
Exception:Vent connectors attached to a mechanical
draft system installed in accordance with the appliance
and draft system manufacturer's installation instructions.
[NFPA 54:12.11.7]
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 commonvent 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]
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.
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 400000 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
applianceflue 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 installation instructions. In the
absence of manufacturer's installation 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 cheeking
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 appliancevent 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.
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 509.3 and
Section 509.3.1 is obtained. [NFPA 54:12.16]
Table 510.1.2(1) through Table 510.1.2(6) shall not be used where obstructions arc installed in the venting
system. The installation of vents serving listedappliances
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) diametervent 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 lateral lengths in Table 510.1.2(1), Table
510.1.2(2), and Table 510.1.2(5) shall not have elbows in
the venting system. Single-appliance venting with lateral
lengths, include two 90 degree (1.57 rad) elbows. For
each additional elbow up to and including 45 degrees
(0.79 rad), the maximum capacity listed in the venting
tables shall be reduced by 5 percent. For each additional
elbow greater than 45 degrees (0.79 rad) up to and including
90 degrees (1.57 rad), 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
offsets combined shall not exceed that specified in Table
510.1.2(1) through Table 510.1.2(5). [NFPA 54:13.1.3]
Local 99% winter design temperature: 37°F or greater
0 0 0 NA NA NA NA
0 0 0 0 NA NA NA
0 0 0 0 123 NA NA
0 0 0 0 190 NA NA
0 0 0 0 249 NA NA
0 0 0 0 184 393 NA
0 0 0 0 0 334 NA
0 0 0 0 0 0 579
6 8 10 15 20 30 50
Local 99% winter design temperature: 27°F to 36°F
0 0 0 NA NA NA NA
0 0 51 NA NA NA NA
68 82 97 NA NA NA NA
116 127 141 NA NA NA NA
156 167 183 233 NA NA NA
180 187 201 253 307 419 NA
212 214 225 274 330 445 NA
266 263 265 305 362 485 763
6 8 10 15 20 30 50
Local 99% winter design temperature:17°F to 26°F
NA NA NA NA NA NA NA
NA NA NA NA NA NA NA
NA NA NA NA NA NA NA
NA NA NA NA NA NA NA
NA 197 214 NA NA NA NA
215 226 245 296 352 NA NA
259 264 278 331 287 507 NA
349 352 358 398 457 581 NA
6 8 10 15 20 30 50
Local 99% winter design temperature: 5°F to 16°F
NA NA NA NA NA NA NA
NA NA NA NA NA NA NA
NA NA NA NA NA NA NA
NA NA NA NA NA NA NA
NA NA NA NA NA NA NA
NA NA 289 NA NA NA NA
NA 312 331 393 450 NA NA
416 423 430 485 547 682 972
6 8 10 15 20 30 50
Local 99% winter design temperature: -10°F to 4°F
NA NA NA NA NA NA NA
NA NA NA NA NA NA NA
NA NA NA NA NA NA NA
NA NA NA NA NA NA NA
NA NA NA NA NA NA NA
NA NA NA NA NA NA NA
NA NA NA NA NA NA NA
484 494 513 586 650 805 1003
Local 99% winter design temperature: -11°F or lower Not recommended for any vent configurations
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:
1 See Figure 510.1.2(6) for a map showing local 99 percent winter design temperatures in the United States.
2 NA: Not applicable.
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)/1.8FIGURE 510.1.2(6)
RANGE OF WINTER DESIGN TEMPERATURES USED IN ANALYZING EXTERIOR MASONRY CHIMNEYS IN THE UNITED STATES
[NFPA 54: FIGURE F.2.4]
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]
Corrugated metallic liner systems installed with bends or offsets shall have their maximum capacity further reduced in accordance with Section 510.1.2. 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]
Where the vertical vent has a larger diameter than the vent connector the vertical ventdiameter 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 listedappliance 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
510.1.2(1) through Table 510.1.2(5) shall be used for
chimneys and vents not exposed to the outdoors below
the roof line. A Type B vent or listedchimney 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 509.6.2,
and where vents terminate in accordance with Section
509.6.2(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. 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. Table 510.1.2(3) in combination with Table
510.1.2(6) shall be used for clay-tile-lined exterior masonry
chimneys, provided the following requirements are met:
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]
For vent heights lower
than 6 feet (1829 mm) and higher than vent heights
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 510.1.2(1) through Table
510.1.2(6), 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 54:13.1.18]
Table 510.2(1) through Table 510.2(9) shall
not be used where obstructions are installed in the venting
system. The installation of vents serving listedappliances 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 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 where the second appliance is a fan-assisted appliance, or the NAT + NAT column where 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 where the
second appliance is a fan-assisted appliance, and the
FAN + NAT column shall be used where 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]
TABLE 510.2(1)
TYPE B DOUBLE-WALL VENT [NFPA 54: TABLE 13.2(a)]*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.
TABLE 510.2(1)
TYPE B DOUBLE-WALL VENT [NFPA 54: TABLE 13.2(a)] (continued)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
TABLE 510.2(1)
TYPE B DOUBLE-WALL VENT [NFPA 54: TABLE 13.2(a)] (continued)*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.
TABLE 510.2(1)
TYPE B DOUBLE-WALL VENT [NFPA 54: TABLE 13.2(a)] (continued)*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.
TABLE 510.2(2)
TYPE B DOUBLE-WALL VENT [NFPA 54: TABLE 13.2(b)]*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.
TABLE 510.2(2)
TYPE B DOUBLE-WALL VENT [NFPA 54: TABLE 13.2(b)] (continued)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
TABLE 510.2(3) MASONRY CHIMNEY [NFPA 54: TABLE 13.2(c)]*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.
TABLE 510.2(3) MASONRY CHIMNEY [NFPA 54: TABLE 13.2(c)] (continued)*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.
TABLE 510.2(4) MASONRY CHIMNEY [NFPA 54: TABLE 13.2(d)]*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.
TABLE 510.2(4) MASONRY CHIMNEY [NFPA 54: TABLE 13.2(d)) (continued)*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.
TABLE 510.2(5)
SINGLE-WALL METAL PIPE ORTYPE B ASBESTOS-CEMENT VENT [NFPA 54: TABLE 13.2(e)]*
The maximum
vent connector horizontal length shall be 18 inches
per inch (18 mm/mm) of connector diameter as shown
in Table 510.2.1, or as permitted by Section 510.2.2.
[NFPA 54:13.2.2]
The vent connector shall be routed to the vent utilizing
the shortest possible route. Connectors with longer horizontal lengths
than those listed in Table 510.2.1 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
510.2.1. For example, the length listed for a 4 inch
(102 mm) connector shall not exceed 6 feet (1829
mm). With a connector length exceeding 6 feet
(1829 mm) but not exceeding 12 feet (3658 mm),
the maximum capacity shall be reduced by 10 percent
(0.90 x maximum vent connector capacity).
With a connector length exceeding 12 feet (3658
mm) but not exceeding 18 feet (5486 mm), the maximum
capacity shall 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 510.1.2(1) shall be used. For single-wall
connectors, Table 510.1.2(2) shall be used. The height
(H) and lateral (L) shall be measured according to the
procedures for a single appliancevent, 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 commonvent to form a commonvent manifold, the
size of the commonvent manifold and the commonvent
shall be determined by applying a 10 percent reduction
(0.90 x maximum commonvent capacity) to the commonvent capacity part of the commonvent tables. The length
of the commonvent manifold (LM) shall not exceed 18 inches per inch (18 mm/mm) of commonventdiameter (D). [NFPA 54:13.2.4]
For each elbow up to and
including 45 degrees (0.79 rad) in the commonvent, the
maximum commonvent 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 commonvent capacity
listed in the venting tables shall be reduced by 10 percent.
[NFPA 54:13.2.6]
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 sha1l be equal to the size of the commonvent. Such fittings shall not be prohibited from having
reduced size openings at the point of connection of appliancegas 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 commonvent. [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.
[NFPA 54:13.2.14]
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 510.1.2(1) or Table
510.1.2(2) for available total height (H) up to the lowest
interconnection. [NFPA 54:13.2.15]
Offsets in
multistory commonvent 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 commonventdiameter of the segment in which the offset is
located.
For the segment of the common vertical vent containing
the offset, the commonvent capacity listed in
the common venting tables shall be reduced by 20
percent (0.80 x maximum commonvent capacity).
A multistory commonvent 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 listedappliance 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 table 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
510.2(1) or Table 510.2(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 510.2(1) or Table 510.2(2). Corrugated metallic
liner systems installed with bends or offsets shall have
their maximum capacity further reduced in accordance
with Section 510.2.5. 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 510.2(1)
through Table 510.2(5) shall be used for chimneys and
vents not exposed to the outdoors below the roof line. A
Type B vent or listedchimney 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 509.6.2, and where vents
terminate in accordance with Section 509.6.2(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 510.2(6) through Table 510.2(9) shall be used for
clay-tile-lined exterior masonry chimneys, provided the
following conditions are met:
The input rating of each space-heating appliance
exceeds the minimum input rating given by Table
510.2(7) (for NAT + NAT) or Table 510.2(9) (for
FAN + NAT).
The vent connector sizing is in accordance with
Table 510.2(3). [NFPA 54:13.2.22]
Vent connectors shall
not be increased more than two sizes exceeding the listedappliance categorized ventdiameter, flue collardiameter,
or draft hood outlet diameter. Vent connectors for draft
hood-equipped appliances shall not be smaller than the
draft hood outlet diameter. Where vent connector sizes
determined from the tables for fan-assisted appliances
are smaller than the flue collardiameter, the use of the
smaller sizes shall be permitted provided that the installation
is in accordance with the following conditions:
Vent connectors for fan-assisted applianceflue collars
12 inches (305 mm) in diameter or smaller are
not reduced by more than one table size [e.g., 12
inches to 10 inches (305 mm to 254 mm) is a one
size reduction] and those exceeding 12 inches (305
mm) in diameter are not reduced exceeding two
table sizes [e.g., 24 inches to 20 inches (610 mm to
508 mm) is a two size reduction].
Combinations of pipe sizes, single-wall metal pipe, and
double-wall metal pipe shall be allowed within a connector
run or within the commonvent, provided the appropriate
tables permit the desired sizes and types of pipe,
where 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 commonvent shall be sized in
accordance with Table 510.2(2) or Table 510.2(4). [NFPA 54:13.2.25]
Where a table permits more than one diameter of pipe to be used for a connector or vent, the permitted sizes shall be permitted to be used. [NFPA 54:13.2.26]
For vent heights lower
than 6 feet (1829 mm) and exceeding vent heights 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 510.2(1) through Table
510.2(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]
