Water source heat pumps: Everything you need to know

Water source heat pumps work by extracting heat from a body of water and turning this into energy that can be used to heat your home and supply you with hot water. As heat transfers better in water, homeowners typically find that they are more efficient than ground and air source pumps.

They are an ideal way to reduce the environmental footprint of your home, especially compared to traditional boilers that rely on fossil fuels such as gas to operate.

Water source heat pumps come in two types: closed loop and open loop system. In general, the closed loop system is more common. The open loop system is only advisable in limited cases. Let's take a closer look at which system is more suitable for your home.

Water source heat pumps tap thermal energy stored in the groundwater by means of two wells: a suction well and a discharge well. With these, the heat pumps can heat and cool.

From the suction well, a pump transports groundwater to an evaporator inside the heat pump. The evaporator passes the groundwater heat on to a liquid refrigerant, causing it to evaporate. This vapour is now compressed and heats up further until it becomes gaseous, and the contained heat is fed into the heat exchanger.

From here, the heat is either passed on directly to radiators or underfloor heating and the domestic water production, or to a buffer storage that supplies the heating system.

The water from which heat was extracted is then led out into the discharge well. The refrigerant passes the heat onto the heating system and re-liquifies. It then reaches the expansion valve that regulates pressure inside the heat pump unit. At the expansion valve, the refrigerant cools down until it can absorb groundwater heat again and the supply loop thus closes.