2003 September 2
Ref: 27038
We have had several answers about SI power of air conditioners.
A minor point has not been mentioned. That is that often in advertisements
the unit is corrupted by leaving out the time unit. This has lead John
Mercer to say the unit for measuring the output of airconditioners is:
"In imperial it's B T U."
The unit is BTU/h. This is an inch-pound unit, that is, it is not SI.
It may or may not be imperial and most of us do not care either way.
The coherent SI unit is watt (W). Usually the power is given in
kilowatts (kW). It is the power in the change in enthalpy of the air
going through the air conditioner. Because most air conditioners remove
moisture as well as cool the air, power goes into two effects,
condensing water and cooling the air. Enthalpy includes both of these.
Robert Bushnell PhD PE
