What is Heat pump?
A '''heat pump''' is a machine that moves [[heat]] from a cold place to a hot place. Examples include:<ref>{{Cite web|title=Heat Pump Systems|url=https://www.energy.gov/energysaver/heat-pump-systems#:~:text=Heat%20pumps%20offer%20an%20energy,and%20the%20warm%20space%20warmer.|access-date=2024-10-30|website=Energy.gov|language=en}}</ref><ref>{{Cite web|last=yifei|date=2024-09-03|title=Best Heat Pump Manufacturers|url=https://www.newntide.com/blog/best-heat-pump-brands-and-manufacturers-of-2024/|access-date=2024-10-30|website=NEWNTIDE|language=en-US}}</ref><ref>{{Cite web|title=8 Manufacturers Complete Heat Pump Challenge {{!}} ACHR News|url=https://www.achrnews.com/articles/163556-8-manufacturers-complete-heat-pump-challenge|access-date=2024-10-30|website=www.achrnews.com|language=en}}</ref><ref>{{Cite web|last=Merrett|first=Neil|date=2024-10-24|title=Heat pump industry heads to Westminster for ‘myth busting’ event|url=https://www.hvnplus.co.uk/news/heat-pump-industry-heads-to-westminster-for-myth-busting-event-24-10-2024/|access-date=2024-10-30|website=Heating and Ventilation News|language=en}}</ref> * [[Refrigerator]]. It moves heat from the inside to the outside. This keeps the food inside cold, so it will not spoil. * [[Air conditioner]]. It moves heat from the inside of a building to the outside. * [[Peltier device]]. It moves heat from one side to the other by means of an electric current. * Some buildings are heated with heat pumps, also. In the [[winter]], the heat pump moves heat from the outside to the inside. Sometimes this works better than heating with a [[radiator]]. == How it works == Usually, heat flows from a hot place to a cold place, according to the [[second law of thermodynamics]]. Heat will not move from a cold place to a warmer place by itself. Because of this, a heat pump must use extra [[energy]] to move the heat. This is sort of like [[pump]]ing water uphill. Most heat pumps use [[electric motor]]s to provide energy. Some heat pumps use heat energy, supplied by a [[flame]] or an [[ele