Things You'll Need
Instructions
Measure the amount of gas used per hour by monitoring your gas meter. Calculate the amount of gas used over a 24 hour period of time and divide it by 24 to obtain the average cubic feet of gas used per hour.
Write down the heat production from a cubic foot of the fuel you use. The heat equivalent of 1 cubic foot of propane and natural gas are 2,500 Btu for propane and 1,050 Btu for natural gas. For example, assume you are using propane gas. The heat produced by 1 cubic foot of propane when burned is 2,500 Btu.
Multiply the flow rate in cubic feet of fuel per hour by the amount of heat produced by 1 cubic foot of fuel. Continuing the example, assume the flow rate of propane was 15 cubic feet per hour. The number of Btu produced per hour is 2,500 Btu / cubic foot of propane x 15 cubic feet / hour = 37,500 Btu per hour.