How does an air source heat pump work?
How it works
- A fan draws outside air over a coil containing a refrigerant, which warms and evaporates.
- A compressor raises the refrigerant's temperature.
- The hot refrigerant gives its heat to your central heating or hot water.
- The refrigerant cools, expands and the cycle repeats.
Why it can be efficient
Because it moves heat instead of making it, a heat pump delivers more heat than the electricity it uses. A seasonal efficiency (SCOP) of 3 means three units of heat for every unit of electricity, compared with under 1 for an electric heater and about 0.9 for a gas boiler.
What it costs to run
A 3-bed home needing 12,000 kWh of heat would use about 4,000 kWh of electricity at a SCOP of 3, costing about £1,080 a year at 27p per kWh. Use the calculator for your own home.
Is a heat pump worth it?
It depends on your home's insulation, the heating system, the prices of electricity and gas, grants and how long you will stay. Well-insulated homes with larger radiators or underfloor heating suit heat pumps best.
Sources and further reading
Questions people ask
Do heat pumps work in cold weather?
Results are estimates for information only, not financial advice. Read the full disclaimer.