Chapter 9 — INSTALLATION OF SPECIFIC APPLIANCES

914.3 Installation.

California Mechanical Code (Title 24, Part 4) · 2022 edition · updated 2026-09-10 · California

Italicized text is a California amendment to the model code, as printed in the official publication.

Non-recirculating direct gas-fired industrial air heaters shall be installed in accordance with the manufacturer’s instructions. [NFPA 54:10.8.3.1]

914.3.1 Fresh Air Ventilation. Non-recirculating direct gas-fired industrial air heaters shall be permitted to provide fresh air ventilation. [NFPA 54:10.8.3.2] 914.3.2 Access Required. Non-recirculating direct gas-fired industrial air heaters shall be provided with access for removal of burners; for replacement of motors, controls, filters, and other working parts; and for adjustment and lubrication of parts requiring maintenance.

[NFPA 54:10.8.3.3]

TABLE 911.2 FREE OPENING AREA OF CHIMNEY DAMPER FOR VENTING FLUE GASES FROM UNLISTED DECORATIVE

	APPLIANCES FOR INSTALLATION IN VENTED FIREPLACES [NFPA 54: TABLE 10.6.2.3]
	MINIMUM PERMANENT FREE OPENING (square inches)*
CHIMNEY HEIGHT (feet)	8	13	20	29	39	51	64
CHIMNEY HEIGHT (feet)	APPLIANCE INPUT RATING (Btu/h)	APPLIANCE INPUT RATING (Btu/h)	APPLIANCE INPUT RATING (Btu/h)	APPLIANCE INPUT RATING (Btu/h)	APPLIANCE INPUT RATING (Btu/h)	APPLIANCE INPUT RATING (Btu/h)	APPLIANCE INPUT RATING (Btu/h)
6	7800	14 000	23 200	34 000	46 400	62 400	80 000
8	8400	15 200	25 200	37 000	50 400	68 000	86 000
10	9000	16 800	27 600	40 400	55 800	74 400	96 400
15	9800	18 200	30 200	44 600	62 400	84 000	108 800
20	10 600	20 200	32 600	50 400	68 400	94 000	122 200
30	11 200	21 600	36 600	55 200	76 800	105 800	138 600

For SI units: 1 foot = 304.8 mm, 1000 British thermal units per hour = 0.293 kW, 1 square inch = 0.000645 m ²

The first six minimum permanent free openings [8 square inches (0.005 m ² ) to 51 square inches (0.03 m ² )] correspond approximately to the cross-sectional areas of chimneys having diameters of 3 inches (76 mm) through 8 inches (203 mm), respectively. The 64 square inch (0.04 m ² ) opening corresponds to the cross-sectional area of a standard 8 inch (203 mm) by 8 inch (203 mm) chimney tile.

2022 CALIFORNIA MECHANICAL CODE 193

INSTALLATION OF SPECIFIC APPLIANCES

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▸Contents — California Mechanical Code (Title 24, Part 4)

California Mechanical Code (Title 24, Part 4)