All heat pump types operate using similar principles – by harvesting energy from the environment and ‘compressing’ it to a temperature that can be used in domestic or commercial applications.
In this case the environment may be
a) the ground or groundwater,
b) the outside air, or
c) warm air as it exits in a property by ventilation. - (Exhaust air heat pump)
The Most popular heat pumps are ground and air source systems:
- Brine* circulates in a collector coil and absorbs the heat energy from bedrock, ground, air or water.
- At the heat exchanger (evaporator) the tepid brine in the collector coil meets the ice-cold refrigerant** in the heat pump, which is then heated a few degrees and evaporates.
- Then, a compressor compresses the refrigerant. The heat that is then generated is transferred via a heat exchanger (condenser) to the house's heating system.
- The refrigerant circulates and an expansion valve lowers the pressure and the refrigerant becomes cold again. The process begins again when the refrigerant meets the tepid brine from the collector coil.
* The brine is a mixture that cannot freeze, for example alcohol or glycol.
** Modern environmentally sound refrigerant are used, e.g. hydrocarbons and carbon dioxide. Formerly, freon was used.
Ground heat pumps harness the stored solar energy from just beneath the ground surface via a horizontal ground loop which is located at a depth of approximately one meter below ground level and at a distance of approximately one meter apart.
This is an ideal system for larger plots of land. The length of ground loops depend on the size of the property and the kW output required from the heat pump.
With an air source heat pump there is no need to dig, drill or have a large plot of land. Instead, the energy is collected directly from the surrounding air using an externally located air handling unit. This can be located up to 30 meters away from the outside of the building for which it is providing heating and hot water.
Northburn Solar has a wealth of knowledge and experience integrating different technologies together.