Heat pumps are seen as the most efficient heat source in heating hot water and domestic hot water. The 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. It 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 often seen as the most environmentally friendly solution. The Galletti air to water heat pump portfolio boasts a huge range of sizes, varying configurations, and a variety of options and accessories.