How Much Does an Air Source Heat Pump Cost in 2026? (UK)
An air source heat pump (ASHP) in 2026 UK costs £7,500–£14,000 fully installed for a typical 3-bed home, after the £7,500 Boiler Upgrade Scheme (BUS) grant. Headline price before grant is £15,000–£21,500. At a real-world SCOP of 3.5 on a 2026 unit cost of 24p/kWh electricity, running cost is broadly on par with a 90% efficient gas boiler — not the dramatic saving some installers promise.
2026 ASHP installed cost by property size
- 1–2 bed flat (6 kW unit): £11,000–£14,500 (£3,500–£7,000 after grant)
- 2–3 bed semi (8 kW): £14,500–£17,500 (£7,000–£10,000 after grant)
- 3–4 bed detached (10 kW): £16,000–£19,500 (£8,500–£12,000 after grant)
- 4–5 bed / poorly insulated (12–14 kW): £18,000–£21,500 (£10,500–£14,000 after grant)
- Hot water cylinder upgrade (mandatory in most cases): £1,400–£2,800 included above
- Radiator upsizing (if required): £200–£380 each
Running cost vs a modern gas boiler (2026)
The honest 2026 maths on a typical 12,000 kWh/year heat demand:
- Gas combi 90%: 12,000 / 0.9 = 13,333 kWh gas at 7.5p = £1,000/yr
- ASHP SCOP 3.0 (poor design): 12,000 / 3.0 = 4,000 kWh elec at 24p = £960/yr
- ASHP SCOP 3.5 (good design): 12,000 / 3.5 = 3,429 kWh elec at 24p = £823/yr
- ASHP SCOP 4.0 (excellent design + low-flow rads): 12,000 / 4.0 = 3,000 kWh elec at 24p = £720/yr
SCOP (Seasonal Coefficient Of Performance) is the lever. Quotes that just promise “a SCOP of 4.5” without an MCS Performance Estimate (MCS PE) are marketing. Always insist on the PE document.
What the £7,500 BUS grant covers
Boiler Upgrade Scheme grant (England & Wales) is £7,500 off an MCS-certified ASHP installation, paid direct to the installer who deducts it from your quote. You don’t apply yourself — the installer does. Eligibility:
- Since the April 2026 rule change, an outstanding loft / cavity insulation note on your EPC no longer blocks the grant on its own — but insulating first still protects your SCOP and running cost
- Existing system is a fossil fuel boiler (gas, oil, LPG) or electric storage heaters
- Property is in England or Wales (Scotland uses Home Energy Scotland up to £15,000)
Net cost after the grant: a 2026 worked example
Take a 2–3 bed semi that needs an 8 kW unit at a mid-range £16,000 installed. Deduct the £7,500 Boiler Upgrade Scheme grant and you pay £8,500 — and because heat pumps are zero-rated for VAT until 31 March 2027, there is no VAT to add on top. Ofgem’s own scheme figures put the average installed ASHP price near £12,500 for an 8 kW system, so a well-shopped quote often lands the net cost between roughly £4,500 and £8,500.
Two 2026 rule changes are worth knowing before you sign. First, from 21 July 2026 an extra £1,500 sits on top of the £7,500 — a total of £9,000 — for homes currently heated by oil or LPG with no mains-gas connection, running until 31 March 2027. Second, the Version 5 scheme rules that took effect on 28 April 2026 removed the old mandatory EPC insulation-recommendations rule, so an outstanding loft or cavity note on your EPC no longer blocks the grant on its own. Insulation still matters enormously for your SCOP and bills, but it is no longer a hard eligibility gate, and the scheme itself now runs to 2030. Full details are on the official Boiler Upgrade Scheme guidance on gov.uk.
For how the sums stack up, see our heat pump grants 2026 breakdown; if you are weighing a straight boiler swap first, read compare boiler types: combi vs system vs heat-only; and to see whether the switch really cuts your bills, our analysis of whether a heat pump is cheaper to run than gas in 2026 runs the numbers.
Hidden cost lines to ask about
- Larger radiators: ASHPs run at lower flow temps (35–50°C), so undersized rads will struggle. A reputable installer will model every room.
- Acoustic mounting: Permitted Development limits noise to 42 dB at the neighbouring property; expect £200–£400 for proper mounts.
- Electrical upgrade: Some older single-phase supplies need a service-head upgrade or load monitor; £0–£800 depending on DNO.
- Time-of-use tariff onboarding: Cosy / Agile-style tariffs add 10–25% to real-world savings but require a smart meter.
Red flags in 2026 ASHP quotes
- No MCS Performance Estimate provided — walk away
- SCOP claimed above 4.5 without underfloor heating — physically very rare
- Installer not on the MCS public register (without it the BUS grant is invalid)
- Unit oversized “to be safe” — over-sized ASHPs short-cycle and run worse
- No room-by-room heat loss survey — a single “whole house” figure is not compliant
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