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Air Source Heat Pump limit of Coefficient Of Performance being less than one?

CliveS

COP is a measure of efficiency a ratio of  Output energy/Input energy.  Thus if 2 kW electric input can give 4 kW of energy output then the COP=2

Google this:-   Can coefficient of performance be less than 1?  Google answer is

"Thus, we can say that the COP of the refrigerator and air-conditioner can be less than one or greater than one. The above formula also shows that the COP of the heat pump can never be less than one; it is always more than one."

I am not sure this final statement is correct because if you are driving the fridge compressor outside the heated room then all the friction power is lost into the atmosphere and not into the refrigerant.  So  if the heat source is more than say 10 degree.C less than the room temperature inside you could be loosing energy rather than saving it?

Parents

  • Another way of looking at it is that it is difficult to extract heat from cold air. So when it is near to freezing in winter, the COP is worst. Granted, a COP of > 1 is better than conventional heating, but what is the payback time compared with say fan heaters?

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  • Another way of looking at it is that it is difficult to extract heat from cold air. So when it is near to freezing in winter, the COP is worst. Granted, a COP of > 1 is better than conventional heating, but what is the payback time compared with say fan heaters?

Children
  • in reply to Chris Pearson

    In the same way that banks will lend you an umbrella when the sun's shining but want it back when it starts raining ASH work best in warm weather . . .

    A COP >1 might be better that conventional electric heating but it's certainly not better than oil or gas. And electric heating is instantaneous and silent and not some great box whirring away outside!

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