How does a heat pump work?

Generally speaking, heat can only be gained from an energy source that has a higher temperature than the immediate ambience. In principle, heat pump technology operates similarly. However, it makes use of the environmental energy stored in the air, ground or groundwater and transfers this to the heating system. This means, it draws from a practically never-ending energy source. In order to utilize the low level of environmental energy in a heating system, use is made of the refrigerant circuit principle.

This process takes place as follows: The cooled liquid refrigerant is first routed to the heat exchanger, the so-called evaporator. Here, the refrigerant absorbs the environmental heat and evaporates in the process. A compressor draws in the now gaseous refrigerant, where it is compressed. This raises the pressure and the temperature rises further. A second heat exchanger (condenser) now ensures that this heat reaches the heating system. The heat transfer lets the refrigerant condense, turning it back into a liquid state. Finally, the pressure reduces in the expansion valve, and the cycle starts again. This principle corresponds to that of a fridge, except the fridge cools instead of heating.

>> A cooled refrigerant is routed, in its liquid state, to the heat exchanger (evaporator). The temperature drop enables it to absorb energy from the environment. In the process, the refrigerant changes into a gaseous state.

>> Inside the compressor, the gaseous refrigerant is compressed. The increase in pressure also raises the temperature.

>> A second heat exchanger (condenser) transports this heat into the heating system; the refrigerant reverts to its liquid form and cools down. 

>> The refrigerant pressure is reduced in the expansion valve. The process starts again.