After the Boiler Upgrade Scheme, an air source heat pump typically costs £5,500 to install, against about £2,500 for a like-for-like combi boiler replacement: £3,000 more up front. At typical efficiency it costs about the same as a boiler to run. So the case for a heat pump rests less on the running costs than on three things: how well it is installed, whether you can drop gas altogether, and what you expect energy prices to do.
What each costs to put in
| Air source heat pump | Gas combi boiler | |
|---|---|---|
| Typical installed price | £13,000 | £2,500 |
| Boiler Upgrade Scheme | less £7,500 | none |
| What you pay | £5,500 | £2,500 |
Typical prices including VAT. A like-for-like boiler swap usually runs from £1,800 to £4,000; moving the boiler, or converting from a system with a hot water tank, costs more.
The heat pump figure is for England and Wales, where the Boiler Upgrade Scheme applies. Scotland runs its own grant through Home Energy Scotland instead. Northern Ireland has no grant for heat pumps at all, so a typical installation there costs the full £11,500.
What each costs to run
At the price cap for 1 October to 31 December 2026, a typical home spends about £870 a year heating with gas, standing charge included. A heat pump at the government trial’s median efficiency would use 2,884 kWh of electricity for the same heat, costing about £760.
The heat pump costs £110 less than gas if it lets you cap the gas supply, and about the same as gas if you keep it for a hob or a fire. Give the boiler a generous 90% efficiency instead and the median heat pump costs £40 more than the boiler on fuel.
The detail, including what raises a heat pump’s efficiency and how tariffs change the picture, is in our guide to heat pump running costs.
Does the extra pay back?
The extra £3,000 up front comes back only through lower running costs, and how quickly depends almost entirely on how efficiently the heat pump runs. These figures assume the gas supply is capped:
| Efficiency (SPF) | Heat pump, a year | Against gas | Pays back in |
|---|---|---|---|
| 2.5 | £850 | £20 less | over 40 years |
| 2.8 (typical) | £760 | £110 less | about 28 years |
| 3.2 | £660 | £210 less | about 15 years |
| 3.6 | £590 | £280 less | about 11 years |
At the trial median, recovering the extra takes about 28 years. A system designed to run at 3.6 does it in about 11 years.
Payback is a narrow way to judge it, though, and the grant has already done a lot of the work: without it, the heat pump would cost £7,500 more still.
What the sums leave out
- Energy prices move. The comparison rests on today’s gap between electricity and gas prices. If electricity gets cheaper relative to gas, the heat pump pulls ahead; if it gets dearer, the gap narrows or reverses.
- VAT on electricity. Household electricity is zero-rated until 31 March 2027, and the figures above include that. After it, on today's prices, the median heat pump costs about £800 a year.
- Space. A heat pump needs room outside for the unit and, in most homes, room inside for a hot water cylinder. A combi boiler needs neither.
- Disruption. A boiler swap is usually a day or two. A heat pump takes longer, and more if radiators or pipework need changing.
- Timing. A boiler that has just failed needs replacing this week. A heat pump needs a survey and a design first, so it’s easier to plan while the old boiler still works.
Which suits you
A heat pump makes most sense if you can cap the gas supply, if your installer designs the system for low flow temperatures, and if you’ll stay in the house long enough for the running costs to count. A new gas boiler still makes sense if you’re moving soon, have no room for a hot water cylinder, or need the heating working again this week.
Either way, get the running costs worked out for your house rather than a typical one. A good heat pump installer will quote an expected efficiency; ask for it in writing.