Heat pump winter efficiency

Published March 11, 2012 by Sean

Here are weekly averages of heat pump performance, for 3 weeks in February 2012. I have referenced them against degree days (16C).

The heat pump has a dedicated electric meter, and I also show the proportion of the whole electric bill which is going to the heat pump. COP is calculated using a heat meter on the output.

D Days   Electric       COP
47.2         74   (54%)  2.36
48.1         77   (48%)  2.35
53.9         130 (88%) 2.08
79.9         155 (70%) 2.06
86.2         190 (74%) 1.78

The heat pump is capable of modulating it’s output, down to about 1.9kW input. Over a week, this is 320 kWh, so even for the colder weeks here (average daily temp 6 degrees), the heat pump is running at around 50% duty cycle – or 25% of full capacity. Flow temperature is set to vary with external temperature, between 30 and 40 degrees for the period shown.

Filed under Heating

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