CALIFORNIA MECHANICAL CODE - MATRIX ADOPTION TABLE
CHAPTER 7 - COMBUSTION AIR
(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
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.
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 701.4 through Section 701.9.3. Where the requirements
of Section 701.4 are not met, outdoor air shall be introduced in
accordance with methods covered in Section 701.6 through
Section 701.9.3.
Appliances of other
than natural draft design and 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]
The required volume of
indoor air shall be determined in accordance with the method
in Section 701.4.1 or Section 701.4.2, except that where the
air infiltration rate is known to be less than 0.40 ACH (air
change per hour), the method in Section 701.4.2 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 701.5, 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 701.5). 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]
Outdoor combustion air
shall be provided through opening(s) to the outdoors in accordance
with the methods in Section 701.6.1 or Section 701.6.2.
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 701.6.1(1) and Figure 701.6.1(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 701.6.1(3)] [NFPA 54:9.3.3.1]
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 701.6.2) 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]
The use of a combination of indoor and outdoor combustion
air shall be in accordance with Section 701.7.1 through
Section 701.7.3. (See Appendix F for example calculations)
[NFPA 54:9.3.4]
The outdoor openings
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 opening(s) shall be not less than
the full size of outdoor opening(s) calculated in
accordance with Section 701.6, 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 rate of
not less than 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]
Ducts shall be constructed of galvanized steel or a material
having equivalent corrosion resistance, strength, and
rigidity.
Exception: Within dwellings 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]
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]
Combustion airducts or
plenums shall not be installed so as to require openings in or
penetrations through construction where fire dampers are
required. Manually operated dampers shall not be installed in
combustion-air openings. With prior approval, power-actuated
movable louvers admitting combustion air shall be
permitted to be used and, where installed, shall be electrically
interlocked with the main burner fuel-supply valve so as to
prevent fuel delivery unless the louvers are in the fully open
position.
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]
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 appliance pressure 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]
