Questions
Short answers to the questions people ask most, each pointing to the guide with the detail.
The answers below are deliberately short. Each topic has its own guide with the reasoning, the figures and the sources. If your question is not here, the form at the foot of the page reaches the publisher, who replies by email.
A pattern runs through them. The physics of a heat pump is settled and well understood; what varies is how well a system is designed and run for a particular home. That is why answers here so often say "it depends", and then say what it depends on.
A machine that moves heat from outside air, the ground or water into a home, using electricity to drive a refrigerant cycle rather than to make heat directly.
The government's rule of thumb is around 3 units of heat per unit of electricity. A large British field trial's interim median for air source systems was 2.80 over a season.
It depends on the two unit prices and the heat pump's real efficiency. On the cap for 1 October to 31 December 2026, a heat pump at 2.8 makes heat at about 9.40p a kWh and a 90% gas boiler at about 8.86p.
Yes. The refrigerant is colder than the outside air even in a frost, so heat still flows into it. Output and efficiency fall in very cold weather, and air source units defrost from time to time; designs are sized for the coldest days.
Some, perhaps. Radiators give out less heat at the lower water temperatures a heat pump prefers, so the design checks each room; some radiators stay, some are replaced with larger ones.
Most heat pump systems store hot water in a cylinder, because they heat water steadily rather than instantly. The government's explainer lists space for one among the things you need.
GOV.UK says the Boiler Upgrade Scheme does not fund hybrid systems. It does contribute £2,500 towards an air-to-air heat pump in a home.
Not on qualifying domestic electricity in Great Britain from 1 October 2026 to 30 June 2027, under HMRC's temporary zero rate.
Among grant-funded heat pumps in England and Wales, 55% replaced mains gas and 18% oil, from May 2022 to September 2026.
No. This is an independent explainer. We do not make, sell or fit heat pumps, and we do not recommend firms or pass your details to them. MCS keeps the official register of certified installers.
Read on 3 November 2026. Where this page and a source differ, the source is right.
Ask about the physics, the efficiency figures, running costs or whether a type suits your home. SEO-DONS LTD, the publisher of this explainer, replies by email. We are not installers and we do not pass your details to any firm.