A brine* circulates in a collector loop and absorbs heat energy from the bedrock, ground, air or water.
In a heat exchanger (evaporator) the tepid brine in the collector loop meets refrigerant** circulating in the refrigerant loop. The tempera-ture is raised a few degrees, the refrigerant evaporates and forms gas.
The pressure of the refrigerant is raised in the compressor, which also raises the temperature to a useable level.
Via a condenser, the refrigerant releases the heat to the heating system for the house, and in connection with this the refrigerant is cooled.
The refrigerant circulates further. The pressure is lowered in an expan-sion valve. It reduces the temperature, the refrigerant returns to liquid form. Process restarts when the refrigerant once again meets the brine.
* Brine is a mixture that cannot freeze, for example alcohol or glycol.
** These days environmentally friendly refrigerants such as carbon dioxide and hydrocarbons are used. Freon was previously used.
Heat pumps work because when a gas is compressed it heats up, while gas that expands becomes colder. Think of a bicycle pump that gets warm when pumping air.
