Guide · last reviewed 3 July 2026
Heat pump vs gas boiler: the honest 2026 comparison
Short version: after the £7,500 grant, a heat pump usually costs more upfront than a boiler swap but less than most people think, runs at similar-or-better cost to mains gas, and lasts longer. And there are still cases where the boiler wins. Here's the whole picture.
Upfront cost
- Like-for-like gas boiler replacement: roughly £2,000–£4,500 installed.
- Air source heat pump: typically £10,000–£14,000 before support — £2,500–£6,500 after the £7,500 Boiler Upgrade Scheme grant (rising to £9,000 for off-gas-grid homes from 21 July 2026).
So post-grant, the gap is real but no longer dramatic — often £1,000–£3,000 on a straightforward install. See our full cost breakdown for what moves quotes.
Running costs — the honest maths
A gas boiler turns one unit of gas into about 0.9 units of heat. A well-designed heat pump turns one unit of electricity into roughly 3–4 units of heat. Electricity costs around four times more per unit than gas under the mid-2026 price cap, so the two roughly cancel out: a good heat pump matches or modestly beats mains gas, and comfortably beats oil, LPG and electric heating. Two caveats that decide the outcome:
- System design. An oversized or badly configured heat pump runs inefficiently and can cost more than gas. Insist on a room-by-room heat loss survey.
- Tariffs. Heat-pump-specific electricity tariffs and time-of-use rates can tilt the running costs clearly in the heat pump's favour. Energy prices change — always check current rates.
When the heat pump clearly wins
- You're off the gas grid on oil, LPG or electric heating — better running costs and the bigger £9,000 grant from 21 July 2026.
- Your boiler is near end of life anyway — you'd spend £2,000–£4,500 regardless.
- You plan to stay 10+ years — the longer lifespan (15–20 years vs 10–15) compounds.
When a gas boiler still makes sense
- Your current gas boiler is young and reliable — replacing it early rarely pays back.
- You're selling soon and won't see the running-cost benefit.
- Your home needs major radiator or insulation work you can't face yet — get the survey anyway; it's often less work than feared.
We'd rather tell you that straight than pretend a heat pump wins every scenario — it doesn't, but the cases where it does are growing every year.
Quick answers
Is a heat pump cheaper to run than a gas boiler?
At mid-2026 energy prices, a well-designed heat pump roughly matches or modestly beats a gas boiler on running costs, and clearly beats oil, LPG and direct electric heating. The design quality matters more than the brand — a poorly designed system can cost more than gas.
Do heat pumps work in old or poorly insulated homes?
Usually yes, if the system is sized properly — that can mean larger radiators and a proper room-by-room heat loss survey. Insulation improves the economics but 'heat pumps only work in new builds' is a myth; they heat homes across much colder countries than the UK.
Should I replace a working gas boiler with a heat pump?
The grant allows it — the old system doesn't need to be broken. Financially it's strongest when your boiler is nearing end of life anyway, or when you're off the gas grid on oil or LPG. If your gas boiler is young and your home is on mains gas, waiting is often reasonable.
How long does each system last?
Heat pumps typically run 15–20 years, gas boilers around 10–15. Over a 15-year horizon you'd often buy two boilers versus one heat pump, which shifts the total cost of ownership in the heat pump's favour.
Decided to look into it?
Based on published Boiler Upgrade Scheme rules, typical installer pricing and Ofgem-capped energy rates as at July 2026. Energy prices and scheme rules change — treat this as general information, not advice, and confirm current figures before committing.