Heat your home this winter with air conditioning.
Your air conditioner already knows how to warm a room — efficiently. Follow the UK heating season from September to March and see how a single inverter unit keeps you cosy for a fraction of the running cost of electric heaters.
Why air conditioning is a smart winter heater
Heat-pump air conditioning doesn't burn electricity to make heat — it moves heat from the outdoor air indoors. That one difference is why it costs so much less to run through the cold months.
~3 kW heat per 1 kW electricity
A heat pump moves heat rather than generating it, so a typical inverter system delivers around 3 units of warmth for every 1 unit of electricity — a SCOP of roughly 3 or higher across the heating season.
A fraction of electric-heater running cost
Because you get 3× the heat per kWh, hour-for-hour running costs are roughly a third of an equivalently sized electric fan or convection heater. See the full breakdown in our savings comparison.
Efficient even below freezing
Modern inverter compressors modulate to keep heating efficiently at outdoor temperatures well below 0°C — far outperforming older reverse-cycle units in a real UK winter.
Autumn to spring, month by month
When you switch to heating mode — and when you switch back — depends on the season. Here is how heat-pump air conditioning fits each stage of the UK autumn and winter.
September
Early autumn
Mild evenings
Nights turn chilly but central heating is overkill. An inverter AC on a low heat setting takes the edge off a cold evening in minutes — quietly and cheaply.
October
Autumn
10–15°C
The "shoulder season" where heat-pump AC shines. Before you fire up the whole-house boiler, warm just the rooms you use and slash standing running costs.
November
Late autumn
5–10°C
Frost arrives. Modern inverter heat pumps still pull warmth from cold outdoor air efficiently, keeping living rooms cosy without blasting the whole house.
December–February
Deep winter
0°C and below
Peak heating season. Heat-pump AC holds a steady set temperature 24/7, eliminating the hot/cold cycling of plug-in heaters while costing a fraction to run.
March
Early spring
Warming up
As days warm, your unit seamlessly switches back to cooling — one system, year-round comfort, no second appliance to buy or store.
Get your unit ready for winter
A few minutes of prep keeps a heat-pump air conditioner heating at peak efficiency through the coldest months.
Winter heating with air conditioning — your questions
When should I switch my air conditioner to heating mode?
Most UK households switch to heating mode from late September or October, when evenings drop to around 10–15°C — the "shoulder season" where warming just the rooms you use beats firing up a whole-house boiler. The same unit flips back to cooling as spring arrives.
Is air conditioning expensive to run for heating in winter?
No — heat-pump air conditioning is one of the cheapest electric heating options available. Because it moves heat rather than generating it, you typically get around 3 kW of heat for every 1 kW of electricity, so running costs are roughly a third of a plug-in electric heater. See our heating vs electric heaters comparison for the numbers.
Does heat-pump air conditioning still work when it is freezing outside?
Yes. Modern inverter heat pumps are designed to heat efficiently at outdoor temperatures well below 0°C. Performance gently reduces as it gets colder, but across a typical UK winter they remain a highly efficient heat source compared with direct-electric heaters or older reverse-cycle units.
Should I use my air conditioner instead of my gas boiler?
Many UK homes use heat-pump AC as their main or supplementary heat source through autumn and winter, warming only the rooms they use rather than the whole house. It pairs perfectly with an existing boiler — zoned, instant, and efficient — and the same unit cools you in summer.
How do I size an air conditioner for winter heating?
Heating sizing follows the same logic as cooling — based on room size, insulation and how cold it gets. Our BTU calculator gives a quick estimate, and our team can size a unit specifically for winter performance. As a rule, the unit that cools a room comfortably in summer will heat it efficiently in winter.
Stay warm this autumn & winter
Browse inverter heat-pump units that cool in summer and heat efficiently all winter — or let us size one for your room.