Air source heat pump FAQs

£8,000 to £14,000 installed for most UK homes, less for a flat, more for large or period property. After the £7,500 Boiler Upgrade Scheme grant in England and Wales, most households pay a net £1,500 to £6,500.

For a typical three-bed semi needing around 12,000kWh of heat a year, roughly £850 to £1,000 annually at a well-designed 45°C flow temperature, rising to £1,150 to £1,350 at a poorly designed 55°C. Roughly line ball with mains gas, clearly cheaper than oil, LPG or electric.

Most UK three and four bedroom houses need 6kW to 12kW, but it comes from a room-by-room heat loss calculation rather than floor area. Never size from your old boiler's output, which is almost always far too large.

Air-to-water heat pumps do, always. They cannot make instant hot water at usable flow rates, so they heat a cylinder gradually and you draw from the store. Air-to-air systems do not provide hot water at all.

Almost never. In a typical three-bed we change four to six and leave the rest. A heat pump runs cooler than a boiler, so radiators need more surface area for the same output, and the heat loss calculation identifies exactly which rooms need it.

Type 22 and Type 33 double and triple panel radiators, because they deliver far more output than a Type 11 in the same wall space. Underfloor heating is better still, and fan-assisted radiators solve tight spaces. Many old cast iron radiators work fine as they are.

Often, though there are more hurdles than in a house. Ground floor flats with private outdoor space are usually straightforward. Upper floor flats face freeholder consent and stricter planning rules, and cylinder space is frequently the binding constraint.

In England and Wales the Boiler Upgrade Scheme pays £7,500 for air source or ground source, £2,500 for air to air, and £9,000 for off-gas-grid homes replacing heating oil between 21 July 2026 and 31 March 2027. In Scotland, Home Energy Scotland pays up to £7,500, or £9,000 rural, plus an interest-free loan.

It depends where you live. In England and Wales your MCS-certified installer applies and the grant is deducted from your invoice. In Scotland you apply yourself to Home Energy Scotland and must be approved before work starts, or you forfeit the funding.

Yes. They extract heat from air well below freezing and are standard domestic heating across Scandinavia. Output and efficiency fall as it gets colder, which is why the system is sized against a regional design temperature rather than an average.

Most domestic installations in England are permitted development. The rules were relaxed in May 2025: the one metre boundary rule was removed, the size cap rose to 1.5 cubic metres and detached homes may have two units. The MCS 020(a) noise assessment still applies. Listed buildings always need consent, and flats and Article 4 areas need checking.

Around 40 to 50dB at one metre, comparable to a fridge in the next room. For permitted development the calculation must come in at or below 37dB(A) at the assessment position for the nearest noise-sensitive window, which determines where the unit can be sited.

Three to five working days on site for most homes, two for a straightforward swap, a week or more for large period properties. End to end from survey to commissioning, four to eight weeks in England and Wales and longer in Scotland.

Roughly line ball for most mains gas households, because electricity costs around three and a half to four times as much as gas per kWh. A heat pump tariff or solar PV tips it clearly in favour. Against oil, LPG or electric heating it wins outright.

For grant funding, yes, in every UK nation that has a scheme. Neither the Boiler Upgrade Scheme nor Home Energy Scotland will pay out on an installation by a non-certified installer. It also gives you a defined standard and a complaints route.

The seasonal coefficient of performance: units of heat delivered per unit of electricity across a year. It is driven mainly by design flow temperature rather than brand. A system at 35°C might achieve 4.0 to 4.5; the same unit at 55°C might manage 2.4 to 2.8.

Not if you want the grant. The existing fossil fuel system must be fully removed or permanently decommissioned, and hybrids are excluded from the Boiler Upgrade Scheme. A correctly sized heat pump should not need a backup.

Air source takes heat from the outside air via an outdoor unit. Ground source takes it from buried loops or boreholes with the heat pump indoors. Ground source is more efficient and cheaper to run but costs two to three times more to install for the same grant, and needs land or drilling access.

Yes, annually. It maintains efficiency, catches refrigerant issues early and is a condition of most manufacturer warranties. Budget £150 to £250 a year.

Typically 15 to 20 years, against 10 to 15 for a gas boiler, with annual servicing.

Nationwide, through MCS-certified regional teams across England, Scotland, Wales and Northern Ireland. Grant support differs by nation, and our regional pages set out what applies where you are.