Are heat pumps suitable for your home?

How a heat pump heats your home

An air source heat pump takes warmth from the outside air and concentrates it to heat your radiators or underfloor heating and your hot water. It runs on electricity, but it moves heat rather than making it by burning fuel. The Energy Saving Trust describes heat pumps as more than three times more efficient than a gas or oil boiler.

The main practical difference from a boiler is the temperature. A heat pump works most efficiently when it heats water to a lower temperature and runs for longer, keeping your home at a steady warmth rather than blasting heat in short bursts. That's why the design of your heating system, and not just the heat pump itself, makes such a difference.

What makes a home suitable

There's no single test. An installer will look at several things together, and a weakness in one area can usually be managed with changes elsewhere.

How much heat your home loses

Every home loses heat through its walls, roof, floors, windows and draughts. A good installer will calculate this room by room, because the result decides the size of heat pump you need and the radiators that go with it.

Better insulation means a smaller, cheaper heat pump and lower running costs. You don't need perfect insulation to get a heat pump, and insulation isn't a requirement for the Boiler Upgrade Scheme, but simple measures such as topping up loft insulation are often worth doing first. Our insulation guide covers where to start.

Your radiators

Because a heat pump runs at lower water temperatures than most boilers, some rooms may need larger radiators to stay warm. This doesn't usually mean replacing every radiator. The heat loss calculation shows which rooms need more heat output and which radiators are already big enough. Underfloor heating suits heat pumps well, because it spreads gentle heat over a large area.

Space outside

The outdoor unit sits on the ground or on a wall, with clear space around it so air can flow through. It shouldn't be boxed in, and it needs to be somewhere the sound won't bother you or your neighbours.

In England, the planning rules for heat pumps on houses were relaxed on 29 May 2025. The rule that a unit had to be at least one metre from your boundary was removed, the size limit was raised, and detached houses can now have two units without planning permission. Installations must meet the MCS noise calculation standard to qualify. Rules are different in Wales, Scotland and Northern Ireland, and for flats, listed buildings and conservation areas, so check with your local council if any of these apply.

Space inside for hot water

Most heat pump systems store hot water in a cylinder rather than heating it on demand like a combi boiler. The Energy Saving Trust suggests a cylinder typically fits in a cupboard of at least 80cm by 80cm. If you have a combi boiler and no airing cupboard, finding this space is one of the bigger questions to settle early.

Your electricity supply

Your installer should check that your electrical supply can take the heat pump, and handle any notification to your local electricity network. This is usually straightforward, but it's worth confirming if you're also planning an EV charger or a battery.

Older homes and flats

A heat pump can work in an older home. The government's Warm Homes Plan notes that 14% of Boiler Upgrade Scheme applicants lived in homes built before 1900. Older homes often lose more heat, particularly through solid walls, so they may need a larger heat pump, more radiator upgrades or some insulation work first. A careful heat loss calculation matters even more here.

Flats bring different questions: where an outdoor unit can go, whether you need permission from the freeholder or management company, and what planning rules apply. Compact units designed for flats exist, but they suit smaller, well-insulated homes best.

What about running costs?

Running costs depend on how well the system is designed, how it's controlled and your electricity tariff. The Energy Saving Trust says that on standard electricity tariffs a heat pump can cost slightly more to run than a new gas or oil boiler, because electricity costs much more per unit than gas. On a tariff designed for heat pumps, running costs can fall far enough that a heat pump costs less to run than a gas boiler. If you disconnect from gas entirely, you also stop paying the gas standing charge.

What it costs, and help available

The Energy Saving Trust puts the typical cost of installing an air source heat pump at around £12,000. The final price depends on the size of heat pump, your property and how many radiators need upgrading.

For the Boiler Upgrade Scheme, your installer applies on your behalf, and the heat pump must be installed and commissioned within 120 days of the application. Grant rules change from time to time, so check the current details on GOV.UK or with Home Energy Scotland before you commit.

Questions to ask an installer

1. Will you carry out a room-by-room heat loss calculation, and can I see it?
2. What water temperature is the system designed to run at, and what efficiency do you expect over a year?
3. Which radiators need changing, and why?
4. Where will the outdoor unit and the hot water cylinder go?
5. Have you completed the noise calculation for the outdoor unit?
6. Are you MCS certified, and will you handle the Boiler Upgrade Scheme application?
7. What warranties come with the heat pump and with your workmanship?
8. How should I set the controls, and which tariffs would you suggest looking at?

Comparing two or three detailed quotes makes it much easier to spot an installer who has taken the time to understand your home.