What is a diversity or demand factor and why apply it?

It accounts for the fact that not every appliance runs at the same moment. A house rarely has the furnace, water heater, and range all firing simultaneously, so 0.80 is a common residential value. Use 1.00 if you must size for full simultaneous demand.

How are BTU/h converted to SCFH?

Divide the BTU/h demand by the fuel's heating value per cubic foot. Natural gas is about 1030 BTU per cubic foot and propane about 2516, so a 100000 BTU/h load is roughly 97 SCFH of natural gas or 40 SCFH of propane.

Should I use connected load or design demand to size the meter?

Size the meter and first-stage regulator to the design demand after the diversity factor, since that reflects realistic peak use. Use the full connected load only when local code or the utility requires sizing for 100 percent simultaneous demand.

Does this size the gas piping?

No. This tool sizes the meter and regulator capacity from total demand. Pipe sizing depends on length, pressure drop, and the longest-run or branch-length method in the fuel gas code, which is a separate calculation.

Which heating value should I use?

The defaults are nominal industry figures. For billing-grade accuracy ask your gas utility for the local higher heating value, which varies with gas composition and can differ by a few percent from the 1030 BTU per cubic foot default.

Gas Appliance Total BTU/h Load Calculator

A gas meter and its first-stage regulator must be able to deliver the peak gas demand of every appliance behind it. This calculator sums each appliance’s BTU/h input, applies a realistic diversity factor, converts the result to standard cubic feet per hour for natural gas or propane, and checks it against the rated meter capacity so you can confirm the service is adequate before you connect a new appliance.

How it works

Three steps turn a list of appliances into a meter capacity check:

connected load = Σ appliance BTU/h
design demand  = connected load × diversity factor
SCFH           = design demand / heating value per cubic foot

The heating value is about 1030 BTU per cubic foot for natural gas and 2516 for propane vapor, so the same BTU/h load draws far fewer cubic feet of propane. The design demand in SCFH is then compared to the meter or regulator’s rated SCFH; if demand exceeds capacity the service is undersized.

Example and tips

A furnace at 80,000, a water heater at 40,000, and a range at 65,000 BTU/h give a connected load of 185,000 BTU/h. With a 0.80 diversity factor the design demand is 148,000 BTU/h, which on natural gas is about 144 SCFH — comfortably inside a 250 SCFH meter. Always confirm the diversity factor your jurisdiction allows; some authorities require full simultaneous demand for commercial kitchens and other high-use occupancies, in which case set the factor to 1.00.