Gas boiler vs heat pump. The honest 2026 maths.
A gas boiler costs less upfront. A heat pump costs less over its life. Here is the head-to-head, the year a heat pump pulls ahead, and the suitability checklist most sites skip.
£14,147 over 10 yr
Lower upfront, plus a replacement around year 12 to 15.
£12,800 over 10 yr
Higher upfront. Pulls ahead around year 6 thanks to lower running cost and longer life.
Head-to-head
| Metric | Gas boiler | Air-source HP | Ground-source HP |
|---|---|---|---|
| Install cost (typical) | £2,500 | £12,000 | £20,000 |
| BUS grant (2026) | n/a | £7,500 | £7,500 |
| Net install cost | £2,500 | £4,500 | £12,500 |
| Annual running cost (3-bed semi) | £1,065 | £680 | £595 |
| Annual service cost | £100 | £150 | £170 |
| Typical lifespan | 12 to 15 yr | 20 to 25 yr | 25+ yr |
| 10-year total cost of ownership | £14,147 | £12,800 | £20,150 |
| 15-year total cost of ownership | £22,471 | £16,950 | £23,975 |
Our model for a typical 3-bed semi, so you can redo it. Install costs are indicative quotes and the 2026 BUS grant is £7,500. The gas running cost is 12,000 kWh at the Q4 2026 Ofgem cap (7.97p/kWh plus 29.68p/day), which comes to £1,065. The heat pump figures assume the same heat delivered at a seasonal COP near 3.5 on an off-peak heat-pump tariff of about 22p/kWh, not the capped standard rate of 26.32p. That tariff assumption is doing real work: on the standard capped rate the same heat pump costs about £830 a year and the crossover slips well past year 10. Heat-pump tariffs are not capped and are priced by region, so check what you can actually get before relying on the year-6 figure. Real installs vary with insulation, fabric and system size.
The crossover year
Cumulative cost over 15 years for a typical 3-bed semi.
| Point in time | Cumulative gas cost | Cumulative HP cost | Notes |
|---|---|---|---|
| Year 0 | £2,500 | £4,500 | Install. Heat pump higher even after grant. |
| Year 5 | £8,324 | £8,650 | Gas still ahead, but only just: £326 separates them. |
| Year 6 | £9,488 | £9,480 | Crossover. The heat pump draws level and goes ahead. |
| Year 10 | £14,147 | £12,800 | Heat pump ahead by about £1,350. |
| Year 12 | £18,977 | £14,460 | Gas boiler hits replacement age, adds £2,500. Heat pump well ahead. |
| Year 15 | £22,471 | £16,950 | Heat pump about £5,500 ahead, still has 5 to 10 years of life left. |
Property suitability
Heat pump is right for you if
- EPC C or above, or you can reach C with insulation
- Outdoor space for a fridge-sized unit on a south or east-facing wall
- Underfloor heating, oversized rads, or you are willing to upgrade
- Mains electricity supply has the headroom for a 16A heat pump load
- You are staying in the home for at least 12 to 15 years
Stick with gas if
- EPC D, E or worse with no insulation budget
- Mid-terrace with no garden access or thin walls
- Standard 600 mm panel rads only, with no upgrade plan
- Selling within 3 to 5 years
- You need replacement now and your boiler has died
BUS grant in 2026
The Boiler Upgrade Scheme pays £7,500 toward an air-source or ground-source heat pump installation. From April 2026, a new £2,500 grant covers air-to-air heat pumps for the first time. The grant is paid by Ofgem direct to your MCS-registered installer, who discounts your invoice. There is no homeowner cashflow cost.
- Eligibility: property in England or Wales, owner-occupier or private landlord, no funding from another scheme for the same install. A valid EPC is no longer required since 28 April 2026.
- Requirement: installer must be MCS-certified and apply on your behalf.
- Timing: application takes 1 to 2 weeks. Grant funds reserved before installation begins.
Full grant guidance on the grants and finance page.
Hybrid systems
A heat pump for the bulk of the heating load, a gas boiler for hot water and the coldest snaps. Hybrid kits cost £4,000 to £8,000 installed. They cut gas use by 60 to 80% without requiring radiator upgrades or full electrification. Worth considering if you cannot reach EPC C with insulation alone.
What about hydrogen?
The UK government decision on hydrogen for domestic heating is expected in 2026. Our view: do not delay a boiler purchase waiting for hydrogen. Most major brands now sell hydrogen-ready models at no real price premium. If hydrogen blending happens, your boiler can be converted by a Gas Safe engineer in a single visit. See the 2035 ban page for the full policy picture.
FAQ
Is a heat pump cheaper to run than gas?
Usually, but the margin depends on your tariff. A modern air-source heat pump runs at a coefficient of performance (COP) of 3 to 3.5 in real UK conditions. A 92% gas boiler delivers heat at 8.66p per useful kWh at the Q4 2026 cap. On the capped electricity rate of 26.32p the heat pump lands between 7.52p (COP 3.5) and 8.77p (COP 3.0), so a good installation beats gas and a mediocre one roughly matches it. On a 3-bed semi that is a saving of about £95 to £235 a year on the capped rate, or £255 to £370 on an off-peak heat-pump tariff near 22p. The gas standing charge you stop paying, £108 a year, is included.How much does a heat pump cost after the grant?
The Boiler Upgrade Scheme grant is £7,500 for an air-source or ground-source heat pump in 2026, paid direct to your MCS-registered installer. A typical ASHP installation of £10,000 to £15,000 falls to £2,500 to £7,500 net. A GSHP at £18,000 to £35,000 falls to £10,500 to £27,500 net.Can I keep my radiators with a heat pump?
Sometimes. Heat pumps run cooler water than a gas boiler (typically 45 to 50°C versus 65 to 75°C), so each radiator delivers less heat. If you have oversized radiators already (common in older homes), you may keep them. Most homes need at least some radiators upsized: typical cost £80 to £150 per radiator including labour. Underfloor heating is the gold standard.What is a hybrid heating system?
A gas boiler and a heat pump working together, with intelligent controls deciding which to use moment by moment. The heat pump handles steady-state demand. The gas boiler kicks in for hot water and very cold days. Hybrid installations cost £4,000 to £8,000. They make sense when full electrification is impractical but you want to cut gas use by 60 to 80%.