Air source heat pumps: cost, running costs and how they work
An air source heat pump takes heat from the outside air, even in winter, and uses it to heat your radiators and hot water. With the £7,500 Boiler Upgrade Scheme grant off the price, it's now one of the most affordable ways to replace a gas, oil or LPG boiler.
Off the installed price with the Boiler Upgrade Scheme.
A good system gives around 3 to 4 units of heat for every unit of electricity it uses.
Typical life of a well-installed, serviced heat pump.
How an air source heat pump works
A fan unit outside draws in air. A refrigerant absorbs its heat, a compressor raises the temperature, and that heat goes into your heating system and a hot water cylinder. It works like a fridge in reverse, and keeps working well below freezing.
- Air-to-water heat pumps (the usual kind) heat radiators or underfloor heating and your hot water, and are covered by the grant.
- You'll need room outside for the unit and inside for a hot water cylinder (roughly the size of a tall fridge).
- Some radiators may be upsized so the house stays warm at a lower, more efficient flow temperature.
- Most homes don't need planning permission: it usually counts as permitted development.
What does an air source heat pump cost?
The price depends on the size of your home, how much heat it loses, and whether radiators or the cylinder need changing. The installer's survey gives you a fixed quote, with the £7,500 grant already taken off.
Running costs: heat pump vs gas boiler
Because a heat pump makes 3 to 4 units of heat from each unit of electricity, running costs are often similar to a gas boiler, and can be lower on a heat pump electricity tariff, in a well-insulated home, or with solar panels and a battery. You also stop paying the gas standing charge if you come off gas completely.
Savings depend on your home, how you use your heating and energy prices. We don't promise a particular saving.
Air source heat pump questions
Do air source heat pumps work in cold weather?
Yes. They keep working well below freezing and are used widely in much colder countries than the UK. Efficiency drops a little on the coldest days, which the installer allows for when sizing the system.
Are air source heat pumps noisy?
Modern units are quiet: the outdoor fan makes a low hum, often compared to a fridge or a gentle breeze. The installer places it to keep sound away from windows and neighbours.
Can I keep my radiators?
Often, yes. Some may need to be larger so the heat pump can run at a lower, more efficient temperature. The survey checks every room.
Do I need a hot water cylinder?
Yes, an air-to-water heat pump heats a hot water cylinder. If you have a combi boiler now, the installer will find space for one, often in a cupboard or the loft.
How much is the grant for an air source heat pump?
£7,500 through the Boiler Upgrade Scheme in England and Wales. It isn't means-tested and you don't need an EPC. See heat pump grants.
Is an air source heat pump better than a gas boiler?
It's much lower in carbon, lasts as long or longer, and with the grant the upfront cost is often close to a new boiler. Running costs depend on your home and tariff, so the installer works them out for you.
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