COP: The Coefficient of Performance is calculated by dividing the amount of heat produced by a heating system divided by the amount of energy put in to it. If the output of a heat pump is 56,000 BTUH (56,000 / 3,412 = 16.4 kW), and the compressor, fan and pumps consume 4.82 kW, the COP is:

16.4 / 4.82 = 3.4

In simple terms, you pay for 4.82 kW to operate the heat pump, and you get 16.4 kW to heat your home. That means you get 16.4 – 4.82 = 11.58 kW from the earth. (You don’t have to pay for those kW)

The efficiency of a gas furnace can be calculated in the same manner. The name plate has two figures: the input, or amount of gas going into the furnace, and the output, or the amount of heat it puts into your home. If the input is 100,000 BTUH, and the output is 92,000 BTUH the COP is:

92,000 / 100,000 = 0.92

Another way of thinking of the COP is:

What you GOT

What you BOUGHT