Boiler vs heat pump: the full picture
Replacing a gas boiler is one of the biggest decisions UK homeowners face. A new condensing gas boiler is the familiar option: DESNZ puts the average at about £3,500 including VAT, and our comparison uses that for a 3 bed home, scaled from £2,950 for 1 bedroom to £4,050 for 5. There is no ban on gas boilers in existing homes; the Future Homes Standard, in force from 24 March 2027 with a one year transition, requires low carbon heating in new homes in England. An air source heat pump costs more upfront: half of those installed under the Boiler Upgrade Scheme cost £11,100 to £15,600, and the £7,500 grant brings that to about £3,600 to £8,100. Whether it pays back depends mostly on the electricity tariff you run it on.
Running costs compared
Gas costs 7.97p per kWh (Ofgem price cap, October to December 2026) and a condensing boiler averages around 90% efficient once a real heating season is taken into account, below the figure on the badge. Electricity costs 26.32p per kWh, but a heat pump delivers several kWh of heat for each kWh of electricity. Measured over a year in 428 homes by the government's Electrification of Heat trial, the median was 2.78, with the middle half between 2.55 and 3.05. That puts heat at about 8.9p per kWh from gas, and 8.6p to 10.3p from a heat pump on a standard tariff, but 6.1p to 7.3p on a heat pump tariff such as Cosy Octopus at about 18.7p per kWh. For an average 3 bed semi that is £666 a year on the tariff against £877 for gas, or £937 on a standard tariff. Over 15 years, counting a £3,500 boiler, the heat pump at £5,200 after the grant and £100 a year servicing for either, the heat pump comes out about £1,465 cheaper on a heat pump tariff and about £2,600 dearer on a standard one. The tariff decides the answer for most gas homes. In a well-insulated home with a properly sized heat pump, running costs are level with or lower than gas.
Why insulation matters so much
Heat pumps operate at lower flow temperatures than gas boilers (often 40 to 50°C against 60 to 70°C). This works well in insulated homes but less efficiently in draughty ones, because the heat pump has to work harder and its COP drops. This is why we always recommend checking your insulation first and improving your EPC rating before installing a heat pump. The order matters: insulate, then install the heat pump.
Frequently asked questions
Is a heat pump cheaper to run than a gas boiler?
On a heat pump tariff, usually yes. On a standard electricity tariff, about the same or a little more: heat costs about 8.9p per kWh from a gas boiler and 8.6p to 10.3p from a heat pump at the efficiencies measured in real homes. On a heat pump tariff such as Cosy Octopus, about 18.7p per kWh with most heating in the cheap hours, that falls to 6.1p to 7.3p.
How much does a heat pump cost compared to a new boiler?
DESNZ puts the average new gas boiler at about £3,500 including VAT. Half of air source heat pumps installed under the Boiler Upgrade Scheme cost £11,100 to £15,600, and the £7,500 grant brings that to about £3,600 to £8,100, so a heat pump usually still costs more upfront.
Will gas boilers be banned?
Not in existing homes. No ban has been set on replacing or repairing a gas boiler in a home that already has one. Under the Future Homes Standard, in force from 24 March 2027 with a one year transition, new homes in England must be built with low carbon heating such as a heat pump.
Should I replace my boiler with a heat pump?
Compare the 15 year cost for your home with the calculator above. For many gas homes a heat pump is cheaper over 15 years on a heat pump tariff and dearer on a standard one. Insulate first where you can, because it lowers the running cost of either system.