701.7 Combination Indoor and Outdoor Combustion

Air. 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. [NFPA 54:9.3.4] (see Appendix F for example calculations)

130 2019 CALIFORNIA MECHANICAL CODE

COMBUSTION AIR

FIGURE 701.6.1(3) COMBUSTION AIR FROM OUTDOORS

THROUGH HORIZONTAL DUCTS

[NFPA 54: FIGURE A.9.3.3.1(2)]

701.7.2 Outdoor Openings. Outdoor openings shall be located in accordance with Section 701.6. [NFPA 54: 9.3.4(2)] 701.7.3 Outdoor Opening(s) Size. The outdoor opening(s) size shall be calculated in accordance with the following: (1) The ratio of interior spaces shall be the available vol ume of all communicating spaces divided by the

(1) The ratio of interior spaces shall be the available vol ume of all communicating spaces divided by the required volume. (2) The outdoor size reduction factor shall be one minus

the ratio of interior spaces.

(2) The outdoor size reduction factor shall be one minus

the ratio of interior spaces. (3) The minimum size of outdoor opening(s) shall be

the full size of outdoor opening(s) calculated in

FIGURE 701.6.2 COMBUSTION AIR FROM OUTDOORS THROUGH

SINGLE COMBUSTION AIR OPENING

[NFPA 54: FIGURE A.9.3.3.2]

701.9.2 Interlock. 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] 701.9.3 Specified Combustion Air. 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]