Gas
Heat input from timed gas volume
- where
- heat input (W; the calculator shows kW)
- measured gas volume (m³)
- volume correction factor
- calorific value at matching reference conditions (J/m³; any unit you pick is converted)
- elapsed time (s)
Explain this equation
Converts a timed meter reading into the heat input an appliance is burning. It is the step after timing the test dial, used to compare a working appliance against its data badge.
V is the gas volume passed in time t. C is a volume correction factor that adjusts the measured volume to the reference conditions the calorific value is quoted at; 1 means no correction. cv is the calorific value, the heat released by burning one cubic metre of gas.
V × C gives a corrected volume, multiplying by cv turns volume into energy, and dividing by t turns energy into power. MJ/m³ and seconds give MJ/s, which the calculator shows as kW.
Sense check: 0.05 m³ in 120 s at 39.5 MJ/m³ gives about 16.5 kW. Double the time for the same volume and the input halves.
Watch out: the manufacturer quotes input on a gross or net basis at stated conditions. Use a cv on the same basis, and don't automatically use the billing correction factor here.
Enter your values to see the result.
Good to know
Gross/net CV basis and volume conditions must match the manufacturer method. Example correction 1 is uncorrected; do not automatically use the billing correction for appliance tests.
Sources
Results are arithmetic only. Worked examples are not recommended design settings. This library does not provide automatic gas pipe selection, live gas tightness tests, purging procedures, combustion acceptance limits, installation approval or commissioning certification. Manufacturer data and the applicable current method remain essential.