UK 2026 / Prices checked 14 November 2026
Gas boiler vs heat pump cost
Upfront cost is the dominant variable today. The Energy Saving Trust puts the average gas boiler replacement at £3,500 (fixed prices start at £1,890 at BOXT). Air source heat pumps installed under the Boiler Upgrade Scheme in July to September 2026 had a median reported cost of £12,826 (DESNZ), about £5,326 after the £7,500 BUS grant.
Side-by-side
| Like-for-like gas boiler | Air source heat pump | |
|---|---|---|
| Upfront cost installed | £3,500 average (EST) | £12,826 median (DESNZ, Jul-Sep 2026) |
| Grant | None typically (ECO4 if eligible) | £7,500 BUS grant (England + Wales) |
| Net cost | £3,500 average (EST) | About £5,326 at the median |
| Install time | 1-2 days | 3-5 days |
| Efficiency | ~93% (A-rated condensing) | ~300% (COP 3.0 typical) |
| Running cost (well-insulated home) | Comparable | Can be comparable |
| Running cost (poorly insulated) | Lower | Often higher |
| Outdoor unit needed | No | Yes (sized to property) |
| Hot water cylinder needed | Only for system/regular | Yes, always |
| EPC requirement | None | Ideally EPC C or better |
| MCS certified installer required | No (Gas Safe is the standard) | Yes (BUS grant requires MCS) |
| Future Homes Standard (England, from 24 March 2027) | Replacement in existing homes still allowed; new homes need low-carbon heating | Meets the low-carbon heating requirement |
When a heat pump wins
- EPC C or better, with cavity wall and loft insulation already done
- Underfloor heating or oversized radiators (heat pumps run at lower flow temperatures)
- Outdoor space for an external unit (typically 1m x 1m footprint plus 30cm clearance)
- Owner-occupier with no plans to move within 5-7 years
- Comfortable with a 4-6 week install lead time vs same-week boiler swap
- Off-gas-grid properties (where the heat pump replaces an oil or LPG boiler with much higher running costs)
When a gas boiler swap wins
- EPC D or worse, with insulation work not yet done
- Older radiators sized for a high flow temperature (60-70 degC) that would need replacing for a heat pump
- Small properties with no space for an outdoor unit
- Cost-constrained replacement: ECO4-eligible households may get a broken, unrepairable boiler replaced (until 31 December 2026; suppliers may ask for a contribution)
- Tenant or short-term owner
- Mains gas connection good and pressure strong
The Future Homes Standard context
The Future Homes and Buildings Standards were published on 24 March 2026 (Building Circular 01/2026) and come into force in England on 24 March 2027. They require low-carbon heating and on-site renewable electricity in new homes, which in practice rules out a gas boiler as the main heat source in a new build. They apply to new buildings, not to replacing a boiler in an existing home, and no date has been set for ending gas boiler replacements in existing homes. If you're replacing a gas boiler today and plan to stay another 15+ years, modelling the heat pump option is worth the effort.
FAQ
How much does an air source heat pump cost installed?
The median reported cost of air source heat pumps installed under the Boiler Upgrade Scheme in July to September 2026 was £12,826, with the middle half between £10,717 and £15,461 (DESNZ). After the £7,500 grant, the median comes to about £5,326.
Is a heat pump cheaper to run than a gas boiler?
Roughly comparable in a well-insulated home (EPC C+); often higher in a poorly insulated home (EPC D-G). A heat pump delivers several units of heat per unit of electricity, but electricity costs about 3.3 times as much per kWh as gas (Ofgem cap, October to December 2026: 26.32p against 7.97p).
What is the £7,500 BUS grant?
The Boiler Upgrade Scheme (gov.uk/apply-boiler-upgrade-scheme) provides £7,500 toward an air source or ground source heat pump installation in England or Wales. £5,000 for biomass boilers in rural off-grid properties. The MCS certified installer applies on the homeowner's behalf.
Should I insulate first or go straight to a heat pump?
Insulate first if you're below EPC C. Loft and cavity wall insulation cut the heat a heat pump has to supply, so a smaller unit runs for fewer hours; going straight to a heat pump in a poorly insulated home is the case where running costs most often end up higher than gas.
Will I be forced to switch eventually?
Not under current published policy. The Future Homes Standard, in force in England from 24 March 2027, applies to new homes. Replacing a gas boiler in an existing home remains permitted, with no published end date.
Going gas? See cost by boiler type. Going heat pump? Start at the BUS grant guide and find an MCS certified installer at mcscertified.com. For deeper running-cost comparison see gasboilercost.com.