From Wikipedia, the free encyclopedia.
A heat pump moves energy in the form of heat from one point (or place with a lower temperature) to another (one with higher temperature). Heat pumps are realized through several physical effects. But they're classified very differently, depending on the used criteria (driving energy, source and sink of heat, or like here: process within a heat pump which is basically a refrigeration machine).
The most common are
- gas compression heat pumps
- phase change heat pumps
- thermoelectric heat pumps use the Peltier effect
- geothermal exchange heat pumps
When comparing the performance of heat pumps, it is best to avoid the word "efficiency", as it has many different meanings. The term coefficient of performance or COP is used to describe the ratio of heat output to electrical power consumption. A typical heat pump has a COP of about three, whereas an electric heater has a COP of just one.

