The refrigerant starts off at ambient temperature and is compressed using an electric motor, which makes it really hot. This hot refrigerant is then used to heat water by passing it through a coil inside a hot water tank, which in turn cools the refrigerant down.
Heat pumps are so efficient that Passive House certification assumes that each occupant will consume 25 L of hot water per day, which can be generated using a heat pump with a seasonal performance factor of 2.25 and associated heat losses, equating to approximately 250 kWh per annum per occupant.
Heat pumps can provide heating and cooling through the same system, and they can be used to cool a home in the same way they are used for heating.
Regarding air-source heat pumps, their cooling efficiency is closely tied to the surrounding environment. As the temperature rises, the system’s efficiency drops, which means that claims of high COPs may not always reflect real-world performance.