Heat Pumps Performance and Efficiency Ratings

Rating performance and efficiency of heat pumps

Several methods are used to rate heat pump performance and efficiency

COP - Coefficient of Performance

The Coefficient of Performance - COP - is the ratio of heat output to the amount of energy input of a heat pump.

COP can be expressed as

COP = h_h / h_w         (1)

where

COP = Coefficient of Performance

h_h = heat produced (Btu/h)

h_w = equivalent electric energy input (Btu/h) = 3.413 P_w

where

P_w = electrical input energy (W)

If a heat pump delivers 3 units of heat for every unit of energy input - the COP is 3.

EER - Energy Efficiency Ratio

The Energy Efficiency Ratio - EER - measures the cooling efficiency of a heat pump.

EER can be expressed as

EER = h_c / P_w         (2)

where

EER = Energy Efficiency Rating

h_c = cooling heat (Btu/h)

P_w = electrical power (W)

Example - EER

An air conditioner or heat pump in cooling modus draws 1000 W to produce 10000 Btu/h cooling. The EER can be calculated as

EER = (10000 Btu/h) / (1000 W)

    = 10

HSPF - Heating Season Performance Factor

The Heating Season Performance Factor - HSPF - is a measure of the overall heating efficiency of a heat pump.

The HSPF can be regarded as an "average" COP for an entire heating season. It is common to compare BTUs of heat output to watts of electrical energy input. HSPF of 6.8 can be compared with an average COP of 2 and a HSPF in the range of 5-7 is acceptable.

SEER - Seasonal Energy Efficiency Ratio

Seasonal Energy Efficiency Ratio is a measure of the seasonal cooling efficiency of a heat pump or a consumer central air conditioning system.

The SEER should be at least 13 to be sold in the United States. SEER above 20 is a very efficient system.

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