The pragmatic definition of the COP is: COP = (What you Get)/(What you Pay For). This measure of performance can have a value greater than unity, and it is this fact that makes a heat pump an ...

The assessment also showed that most high-performance (COP larger or equal to 3.2) and costly (price of more than 750 £/kWth) heat pumps had large heat exchangers and rotary vane or scroll ...