British Thermal Units and Boilers

Boiler Capacities are often denoted in British Thermal Units.  One British Thermal Unit is defined as the amount of heat required to raise one pound of water by one degree Fahrenheit.  While the BTU has generally been replaced with the more popular unit, the Joule, Boilers and the Heating industry still use the British Thermal Unit.

One BTU is equal to 1.06 Joule

BTUs are also used for indicating the energy in fuels.  Oil has a BTU of 138000  per gallon.  Natural Gas has a BTU of 1075 per cubic foot.

A bigger unit is the MMBTU which stands for one million BTU.  The M  is the Roman number for thousand.  MM stands for a thousand thousand which is one million.