Device for efficient energy transfer from cold to warm.

A Heat pump is a device that uses work to transfer energy from cold to warm. Heat pumps can be a sustainable alternative for domestic or commercial heating, as electric heat pumps have no combustion at the point of use and are much more efficient than direct electric heating, because they can transfer up to 3–6 units of heat using a single unit of energy. Most heat pumps are powered by electricity, but heat pumps powered by natural gas exist as well. They are a popular choice in the decarbonisation of heating, in particular in areas where district heating is not expected. In many countries, the high upfront investment cost is subsidised, such that they quickly pay off not only energetically but economically as well.

Broadly speaking, heat pumps can be categorised based on their heat source, such as outside air, exhaust air, geothermal, shallow earth, groundwater, surface water or even ice, and their heat sink, typically air or water (for use with central heating or for hot water). They can be combined with other sources of heating, such as solar, fossil, or wood. In buildings with central heating, air-to-water heat pumps are the most popular replacement for existing fossil-fuel boilers, as the pre-existing central heating can often remain in place with little or no changes, although they work most efficiently with very large radiators such as underfloor heating.

Use this tag for questions about transitioning heating to heat pumps, about different types of heat pumps, or about other related questions.