How a heat pump works |
- A brine* circulates in a collector loop and absorbs heat energy from the rock, ground, air or water.
- The heat pump contains a heat exchanger called an evaporator. The energy is transferred to a refrigerant** with a low boiling point which evaporates and circulates as gas in a closed system.
- The pressure of the refrigerant is raised in the compressor, which also raises the temperature to a useable level.
- In the condenser, the refrigerant releases the heat to the heating system for the house.
- The separate cooler functions as an extra heat exchanger and squeezes out the remaining heat energy at which point the refrigerant returns to liquid form.
- The pressure falls in the expansion valve.
- The refrigerant returns to the evaporator and the process starts again.
* Brine is a mixture which cannot freeze, for example alcohol or glycol. ** These days environmentally friendly refrigerants such as carbon dioxide and hydrocarbons are used. Freon was previously used.

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