Ground Source Heat Pumps
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How They Work
Heat Pumps operate in a similar way to a refrigerator – but in reverse. Heating and cooling are achieved by moving a refrigerant through various indoor and outdoor coils and components. A compressor, condenser, expansion valve and evaporator are used to change the state of refrigerant from a liquid to hot gas and from a gas to cold liquid.
The main stages of the process are as follows:
- Liquid refrigerant passes through the outdoor evaporator coils at a low temperature.
- Liquid from the ground loop enters the unit and heat is transferred from this liquid to the refrigerant. As a result, the refrigerant boils and becomes vapour.
- The vapour is drawn into the compressor, where the temperature of the vapour is increased to over 100 degrees.
- The vapour then enters the condenser heat exchanger and heat from the vapour is transferred across the coils. As the vapour cools it condenses back to a liquid, which releases considerable latent heat to the air passing over the heat exchanger.
- The refrigerant, which is now a very cold liquid at high pressure, passes through an expansion valve, which reduces the pressure so that the cold liquid can re-enter the evaporator and begin the cycle again.
At stage 4, the heat is transferred to the buildings heating, cooling and hot water systems.