How Do Heat Pumps Work?

A heat pump uses technology to air conditioning (but in reverse) and extracts heat from a source, such as the surrounding air or the ground. It then transfers the heat to where it is needed. Because most of the heat is transferred rather than generated, heat pumps are far more efficient than conventional heating technologies such as boilers or electric heaters and can be cheaper to run.

The output of energy in the form of heat is normally several times greater than that required to power the heat pump, normally in the form of electricity. For example, the coefficient of performance (COP) for a typical air source heat pump is around 4, meaning the thermal energy output is four times greater than the electrical energy used to run it, making them 3‐5 times more energy efficient than gas boilers.

The heat pump itself consists of a compressor, which moves a refrigerant through a refrigeration cycle, and a heat exchanger, which extracts heat from the source. The heat is then passed on to a heat sink through another heat exchanger. In buildings, the heat is delivered using either forced air or hydronic systems such as radiators or under‐floor heating. Heat pumps can be connected to a tank to produce domestic hot water.