How Air Source Heat Pumps Work
A clear, jargon-free explanation of how an air source heat pump takes warmth from the outside air to heat your home and hot water.
- Last reviewed: July 2026
- Reading time: 6 minutes
Key takeaway
A heat pump gathers free warmth from the outside air and delivers several units of heat for every unit of electricity it uses — an efficient, low-carbon way to heat your home.
How a heat pump heats your home
An air source heat pump sits outside your home and draws warmth from the outside air — even on a cold day. It passes that warmth through a system that raises the temperature further, then uses it to heat your radiators, underfloor heating and hot water. Because it moves heat rather than burning fuel, it is remarkably efficient.
What makes a heat pump different
- It takes free warmth from the outside air
- It works even when it feels cold outside
- It produces more heat than the electricity it uses
Why it is so efficient
A traditional boiler burns gas or oil, so at best it turns one unit of fuel into a little under one unit of heat. A heat pump does something clever: for every unit of electricity it uses, it can deliver several units of heat by gathering warmth from the air. That efficiency is what helps lower your running costs.
Where the savings come from
- Heat from the air
- Warms your whole home
- Low-carbon heating
A heat pump running through the year
In milder months a heat pump barely has to work to keep your home warm. In the depths of winter it works a little harder, but it keeps running efficiently even in freezing conditions — which is why heat pumps are so widely used in far colder countries than the UK. Once it is set up, it quietly heats your home day and night with very little for you to think about.
Frequently asked questions
Do heat pumps work in cold weather?
Yes. Air source heat pumps are designed to keep working in freezing conditions and are used successfully across some of the coldest countries in the world. As long as your system is sized and installed correctly, it will keep your home warm right through a British winter.
Is a heat pump noisy?
Modern heat pumps are quiet — most people compare the sound to a fridge humming gently. The outdoor unit is positioned carefully during installation to keep any noise to a minimum for you and your neighbours.
Can a heat pump provide hot water?
Yes. As well as heating your home, an air source heat pump heats your hot water, usually stored in a hot water cylinder ready for when you need it. We will make sure the system is set up to meet your household’s hot water needs.
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Last reviewed: July 2026 · Reviewed by: Warmr Heating Team