BRITISH THERMAL UNIT
The amount of heat required to change the temperature of one pound of water one degree Fahrenheit at sea level.
The quantity of heat required to raise the temperature of 1 pound of liquid water by 1 degree Fahrenheit at the temperature at which water has its greatest density (approximately 39 degrees Fahrenheit).
British Thermal Unit, BTU, the amount of heat required to raise the temperature of one pound of water by one degree Fahrenheit.
(Btu) - The standard measure of heat energy. It takes one Btu to raise the temperature of one pound of water by one degree Fahrenheit at sea level. For example, it takes about 2,000 Btus to make a pot of coffee. One Btu is equivalent to 252 calories, 778 foot-pounds, 1055 joules, and 0.293 watt-hours. Note: In the abbreviation, only the B is capitalized.