How does a Heat Pump Work?
Heat pumps use a refrigerant cycle to transfer heat from a source such as air, ground or water to the medium to be heated, in this case the water in central heating systems. The cycle is similar to a fridge where the source is within the fridge and the heat is transferred outside the fridge. The cycle comprises:
Evaporation
The refrigerant passes through a heat exchanger where it evaporates absorbing heat from the source.
Compression
The heated refrigerant is then compressed to a higher pressure using an electrically driven compressor.
Condensation
The compressed refrigerant passes through another heat exchanger located in the space to be heated and condenses, changing back to a liquid and releasing heat in the process.
Expansion
The liquid refrigerant passes through an expansion device lowering its pressure prior to returning to the evaporator to repeat the cycle.
For households the source can be air but it can also be ground and water if available. Heat pumps can be connected to a “wet” heating system comprising radiators and it is possible to use the existing heating system when retrofitting.
Heat pumps use a refrigerant cycle to transfer heat from a source such as air, ground or water to the medium to be heated, in this case the water in central heating systems. The cycle is similar to a fridge where the source is within the fridge and the heat is transferred outside the fridge.
The cycle comprises: Otherwise, the existing radiators may need to be replaced with larger heat capacity units to compensate for the lower water flow temperatures. The main advantage of heat pumps is their operating efficiency which typically averages 300% thereby reducing their running costs. Hence the electricity consumption is much less than other forms of electric heating but their capital cost is much higher.
All heat pumps have the basic need for an evaporator and condenser which perform the function of drawing heat in from a source and expelling it (respectively).
They also need a form of circulator which is a compressor in vapour compression cycle or a ‘solution pump’ in an absorption process.
For more information about work undertaken by the Association, please email info@heatpumps.org.uk or call us on 0118 940 3416