How Do Heat Pumps Work? A Simple Guide for UK Homes
How does a heat pump heat your home from cold outside air? Heat pumps explained simply, with the pros, cons and costs to think about.
Heat pumps are becoming a common sight outside UK homes as an alternative to gas boilers. But how can a machine heat your home using cold air from outside? Here's the science in plain English.
The basic idea
A heat pump doesn't make heat by burning fuel. Instead, it moves heat from outside into your home. It works like a fridge in reverse. A fridge takes heat from inside the box and releases it at the back. A heat pump takes heat from the air or ground outside and releases it inside your home.
Even cold winter air contains some heat energy, and a heat pump can collect it.
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How it works, step by step
1. Collect. A fan blows outside air over pipes containing a special fluid called a refrigerant. The refrigerant is so cold that it absorbs heat from the air and turns into a gas.
2. Squeeze. A compressor squeezes the gas. Squeezing a gas makes it much hotter, a bit like a bike pump getting warm.
3. Release. The hot gas passes its heat to the water in your radiators, underfloor heating and hot water tank.
4. Repeat. The refrigerant cools, turns back into a liquid, and the cycle starts again.
Why heat pumps are efficient
Because a heat pump moves heat rather than making it, it can deliver more heat energy than the electricity it uses. A good heat pump often produces around three units of heat for each unit of electricity, sometimes more. A gas boiler can never produce more heat than the energy in the gas it burns.
Types of heat pump
- Air source heat pumps take heat from the outside air. They're the most common type in the UK and the easiest to install.
- Ground source heat pumps take heat from pipes buried in the garden. They're very efficient but cost more to install and need more space.
Things to think about
- Insulation matters. Heat pumps work best in well-insulated homes.
- Lower, steadier heat. They usually run at lower temperatures for longer, so your home feels evenly warm rather than heating up quickly.
- Radiators. Some homes need bigger radiators.
- Grants. Government grants for heat pumps have been available in parts of the UK, such as the Boiler Upgrade Scheme in England and Wales. Check GOV.UK for the latest amounts and rules.
- Running costs depend on your home, your electricity tariff and how well the system is installed.
Common questions
Do heat pumps work in winter?
Yes. Modern heat pumps are designed to work in sub-zero temperatures, though they become a little less efficient as it gets colder.
Are heat pumps noisy?
Air source heat pumps make a low humming noise, similar to a fridge or air conditioning unit. Installers must follow rules on placement and noise.
Is a heat pump cheaper to run than a gas boiler?
It depends on your home, energy prices and your tariff. Some electricity tariffs are designed for heat pump owners and can lower running costs.
Can I get a grant for a heat pump?
Grants have been available in England and Wales through the Boiler Upgrade Scheme, and Scotland has its own schemes. Check the government websites for the latest details.
Related guides
- Why Do Leaves Change Colour in Autumn?
- How to Sleep Better in Winter
- How to See the Northern Lights in the UK
This guide is for general information only. Prices, rules and offers can change, so always check the latest details before you decide.
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