Heat pumps work by using the natural heat energy produced by the sun. This, in turn, is absorbed into the earth’s surface, water and air, which act as giant heat stores.

The ground loop array or heat collector absorbs this low temperature heat from the surrounding ground, water or air, and transports this heat to the heat pump.

At the heat pump, the collected heat from outside (‘the source’) is passed over the ‘evaporator heat exchanger’ – here the heat is absorbed by the refrigerant gas within the heat pump. The refrigerant in the evaporator is colder than the heat source which causes the heat to move from the heat source to the refrigerant making the refrigerant gas evaporate.

The refrigerant gas is put through a compressor which vastly increases the temperature and pressure of the gas. (Like if you were to hold your finger over a bicycle pump and pump away…..your finger gets hot, you create heat by compression!). The hot, high pressured gas is passed over another heat exchanger called ‘the condenser’. Here the heat is passed onto the load/heat distribution side – typically underfloor heating, radiators or hot water systems.

Now that the refrigerant gas has passed over most of its heat it is pushed through an expansion valve where the gas expands and therefore drops in pressure and cools – the refrigerant gas then picks up more heat from the heat source and the cycle starts again. The ground or ‘heat sink’ used is a constant supply because it will always be re-charged by the sun - hence the term ‘renewable energy’.