BTU (British Thermal Unit)

BTU stands for British Thermal Unit, a unit of measurement that shows how much energy your air conditioner uses to remove heat from a room in one hour (for cooling ) or how much energy it uses to heat the room (when measuring heating ).

The terms BTU and BTU/h (BTU per Hour) are used interchangeably, but technically the correct expression is BTU/h. Air conditioners extract heat from indoor air and move it outdoors, which is the same as saying that air conditioners move energy. A BTU is the amount of energy needed to raise the temperature of one pound of water one degree Fahrenheit at sea level. The BTU rating indicates the power of the unit, also referred to as the size of the unit. For example, a unit labelled 8,000 BTUs can produce 8,000 BTUs of energy over the course of an hour. This is technically known as the BTU/hour rating, although it is often stated simply as BTU.

The other three most common ways are other ways of measuring or stating the capacity of the unit which may be converted from BTU. 1 BTU is equivalent to:
0.0003 kW (or more easily 1kW = 3,412 TBU)
0.00008333333333 Tons (or more easily 1 Ton = 12,000 BTU)
0.0001111111111 (or more easily 1HP = 9,000 BTU)

For proper operation of the unit, and to avoid unnecessary energy consumption, it is important that the unit is correctly sized in relation to the space being cooled.

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