What is a BTU?
A British Thermal Unit is the amount of energy needed to raise one pound of water by one degree Fahrenheit. In HVAC, BTU per hour (BTUh) measures the heating or cooling output of equipment. One ton of cooling equals 12,000 BTUh, and one kilowatt equals approximately 3,412 BTUh.
When comparing heating equipment, BTU input is the fuel energy consumed while BTU output is the useful heat delivered. The ratio of output to input is the efficiency (AFUE for furnaces, COP for heat pumps).
1 ton = 12,000 BTU/h
One ton of refrigeration removes 12,000 BTU of heat per hour.
1 kW = 3,412 BTU/h
Conversion between electrical power and thermal energy rate.