Heat pumps are seen as the most efficient heat source for heating hot water. A heat pump unit draws energy into the system from the external environment - this energy is extracted from a source such as water, the ground or most commonly the air. Energy is then transferred to the system water via a refrigerant cycle.

Many heat pumps are reverse cycle so they can provide cooling as well. With no combustion process, they are one of the most environmentally friendly solutions. CO2 or EcoCute heat pumps are free of chemical refrigerants, using natural CO2 instead. So you achieve environmental benefits and gain the option of producing up to 90⁰C water at COPs of up to 4.2.