Do Heat Pumps Work in Winter?
Yes. Heat pumps work in winter and keep heating your home well below freezing. Air source models are rated to run down to about minus 15 to minus 25°C, far colder than a typical UK winter. They are used across Scandinavia, where winters are much harsher than ours. What changes in the cold is efficiency: a heat pump produces less heat per unit of electricity as the outside air drops, so it works harder and costs a little more to run on the coldest days.
Quick Answer
Yes, heat pumps work in winter. Air source heat pumps are rated to operate down to roughly minus 15 to minus 25°C, well below a normal UK winter. They become less efficient as it gets colder, so running costs rise on the coldest days, but a correctly sized and installed unit keeps a UK home warm year round.
Guidance as of early 2026, based on UK heat pump practice.
Fact-checked by John Rooney, Solar Energy Editor. Editorial policy
How heat pumps work in cold weather
A heat pump does not burn anything to make heat. It moves heat that is already in the outside air into your home, even when that air feels cold to us. There is usable heat energy in air well below zero, which is why an air source heat pump keeps working when frost is on the ground. On very cold mornings it runs a brief defrost cycle to clear ice off the outdoor unit, then carries on heating. Ground source heat pumps are steadier still, because the ground a metre or two down stays around 8 to 12°C all year, so winter barely changes their performance.
| Outside Temperature | What Happens |
|---|---|
| 7°C (UK rating point) | Efficient, typical mild winter day |
| 0°C | Still efficient, occasional defrost cycle |
| Minus 5°C | Works well, efficiency dips, costs a little more |
| Minus 15 to minus 25°C | Most units still operate at their rated low limit |
How efficient are heat pumps in winter?
Efficiency is measured by the coefficient of performance, or COP: how many units of heat you get per unit of electricity. On a mild day a good air source heat pump returns around 3.5 to 4 units of heat per unit of power. On a very cold day that can fall to around 2 to 2.5, which is still well ahead of a direct electric heater at 1. Across a whole UK winter the seasonal average (SCOP) usually lands between about 3 and 4. Ground source systems hold a higher figure because their heat source stays warm. See the full heat pump running cost breakdown.
Will a heat pump keep your home warm?
An MCS-certified installer sizes the system to your home and local winter design temperature. Get free quotes near you.
Get a Quote →Do heat pumps work in old houses?
Yes, including period and solid-wall homes, but the result depends on heat loss. An older house leaks more heat, so it needs a larger heat pump and sometimes a few upsized radiators to stay warm at a low flow temperature. Basic insulation, loft and draught-proofing first, helps the system run cheaper. The heat loss survey is what tells an installer whether your home is ready as-is or needs a little work. See which radiators may need upsizing.
Do heat pumps work in Scotland?
Yes. Scotland is colder than the UK average, but still milder than the Nordic countries where heat pumps are standard. They are widely installed across Scotland, and Home Energy Scotland offers grants and interest-free loans on top of the UK schemes. A correctly sized unit handles a Scottish winter; the main effect of the colder climate is a slightly lower seasonal efficiency than in the south of England. See heat pump grants.
Heat Pumps in Winter FAQ
Do heat pumps work in winter?
Yes. Heat pumps keep heating your home through winter and well below freezing. Air source units are rated to run down to roughly minus 15 to minus 25°C, far colder than a normal UK winter, which is why they are standard across Scandinavia.
What temperature do heat pumps stop working at?
Most air source heat pumps are rated to keep operating down to about minus 15 to minus 25°C, depending on the model. UK winters very rarely reach those temperatures, so in practice a heat pump keeps working all winter.
Are heat pumps less efficient in cold weather?
Yes, a little. A heat pump returns less heat per unit of electricity as the outside air gets colder. On a mild day a good air source unit returns around 3.5 to 4 units of heat per unit of power; on a very cold day that can fall to around 2 to 2.5, still well ahead of direct electric heating.
Do heat pumps work in old houses?
Yes, including solid-wall and period homes, but an older house loses more heat, so it needs a larger heat pump and sometimes a few upsized radiators. Basic insulation and draught-proofing first keeps running costs down. A heat loss survey confirms what your home needs.
Do heat pumps work in Scotland?
Yes. Scotland is colder than the UK average but milder than the Nordic countries where heat pumps are normal. A correctly sized unit handles a Scottish winter, and Home Energy Scotland offers grants and interest-free loans on top of the UK schemes.
Do air source heat pumps freeze up in winter?
Frost can build on the outdoor unit in cold, damp weather, so the heat pump runs a short automatic defrost cycle to clear it and then carries on heating. This is normal and built into how the unit works.
Find a heat pump installer near you
An MCS-certified installer sizes the system for your home and local winter conditions.
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Sources
Last updated: June 2026
John Rooney is the founder of Solar Info and has been covering the UK solar energy market since 2023. He researches every battery and inverter brand against manufacturer datasheets, MCS and Ofgem data, and feedback from the MCS-certified installers in our directory before publishing.
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