1208.3 Sizing of Gas Piping Systems — 2025 California Plumbing Code
California Plumbing Code (Title 24, Part 5) · 2025 edition · updated 2026-10-19 · California
CBSC: official editions, supplements and errata
Italicized text is a California amendment to the model code, as printed in the official publication.
Cite as: 2025 California Plumbing Code (Title 24, Part 5) § 1208.3 · Effective January 1, 2026 · Official source: Building Standards Commission
Gas piping systems shall be of such size and so installed as to provide a supply of gas sufficient to meet the maximum demand and supply gas to each appliance inlet at not less than the minimum supply pressure required by the appliance. [NFPA 54:5.3.1]
1208.3.1 Maximum Gas Demand. The volumetric flow rate of gas to be provided shall be the sum of the maximum input of the appliances served. The volumetric flow rate of gas to be provided shall be adjusted for altitude where the installation is above 2000 feet (610 m). [NFPA 54:5.3.2.1 – 5.3.2.2] Where the input rating is not indicated, the gas supplier, appliance manufacturer, or a qualified agency shall be contacted, or the rating from Table 1208.3.1 shall be used for estimating the volumetric flow rate of gas to be supplied.
The total connected hourly load shall be used as the basis for piping sizing, assuming all appliances are operating at full capacity simultaneously.
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Exception: Sizing shall be permitted to be based upon established load diversity factors. [NFPA 54:5.3.2.3]
TABLE 1208.3.1
APPROXIMATE GAS INPUT FOR
TYPICAL APPLIANCES
[NFPA 54: TABLE A.5.3.2.1]
| APPLIANCE | INPUT (Btu/ |
|---|---|
Space Heating Units Warm air furnace Single family Multifamily, per unit Hydronic boiler Single family Multifamily, per unit |
100 000 60 000 100 000 60 000 |
Space and Water Heating Units Hydronic boiler Single-family Multifamily, per unit |
120 000 75 000 |
Water Heating Appliances Water heater, automatic storage 30 to 40 gallon tank Water heater, automatic storage 50 gallon tank Water heater, automatic instantaneous Capacity at 2 gallons per minute Capacity at 4 gallons per minute Capacity at 6 gallons per minute Water heater, domestic, circulating or side-arm |
35 000 50 000 142 800 285 000 428 400 35 000 |
Cooking Appliances Range, freestanding, domestic Built-in oven or broiler unit, domestic Built-in top unit, domestic |
65 000 25 000 40 000 |
Other Appliances Refrigerator Clothes dryer, Type 1 (domestic) Gas fireplace direct-vent Gas log Barbecue Gaslight |
3000 35 000 40 000 80 000 40 000 2500 |
For SI units: 1000 British thermal units per hour = 0.293 kW
1208.3.2 Sizing Methods. Gas piping shall be sized in accordance with one of the following:
(1) Pipe sizing tables or sizing equations in this chap ter.
(2) Sizing tables included in a listed piping system manufacturer’s installation instructions.
(3) Engineering methods. [NFPA 54:5.3.3]
1208.3.3 Allowable Pressure Drop. The design pressure loss in a piping system from the point of delivery to the inlet connection of all appliances served shall be such that the supply pressure at each appliance inlet is greater than or equal to the minimum pressure required by the appliance. [NFPA 54:5.3.4]
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