Heating systems

Air source heat pumps

How do they work?
What are the benefits?
Is it the right kind of heat pump for me?
Installation costs
What funding is available?
Will I save money?
How do I get one installed?
Heat pump stories

An air source heat pump (sometimes called an air-to-water heat pump) transfers heat from the outside air to the water in your central heating system. This heats rooms in your home via radiators or underfloor heating. It can also heat water stored in a hot water cylinder for your hot taps, showers, and baths.

Let’s look at the benefits, their installation costs and how much you could save on your energy bills.

How does an air source heat pump work?

Air source heat pumps take heat from the air and transfer it to a fluid refrigerant. This fluid passes through a compressor, which raises the fluid’s temperature and transfers the heat to your central heating system.

For a more detailed look at how they work, see our in-depth heat pump guide.

What are the benefits of air source heat pumps?

There are several benefits of air source heat pumps:

Lower your energy bills: depending on what heating system you’re replacing, you can save money on your energy bills.
Reduce your energy use: unlike traditional boilers (which use fossil fuels), heat pumps use electricity. And heat pumps are more than three times more efficient than a gas or oil boiler, helping to lower your energy use.
Improve your carbon footprint: your CO₂ emissions will be lower with a heat pump compared other types of heating. This is because they don’t use fossil fuels, instead taking heat from their environment.

Is an air source heat pump right for me? 

Air source heat pumps are the most common type of domestic heat pump in the UK and are suitable for most types of homes. There are a few things you should consider before deciding whether a heat pump is right for you.

There are two main types: monobloc and split systems.
- A monobloc system has all the components in a single outdoor unit. Pipes carry water to the central heating system and a hot water cylinder inside your home.
- A split system separates the heat pump into indoor and outdoor units.
Monobloc systems tend to be more common because they’re cheaper and quicker to install. They don’t take up as much space inside your home, but they’re slightly less efficient than split systems.

Split systems can be more efficient because some of the heat transfer takes place inside the building where it’s warmer, resulting in less heat being lost.
A standard air source heat pump doesn’t provide hot water on demand like a combi boiler. So, when you’re thinking about your heating options, you’ll need a way of storing hot water for when you need it:

Hot water cylinders

The size of hot water cylinder depends on the amount of hot water your household typically uses. They can usually fit inside any cupboard that measures at least 80cm x 80cm.

Other options

If you don’t have space for a hot water cylinder, you still have options. For example, some hybrid heat pump systems have the heat pump providing heating and a boiler providing hot water on demand.

You could also consider installing a heat battery, which takes up less space than a hot water cylinder.

Instantaneous hot water heaters are also available. You can install these under your kitchen sink to provide a smaller amount of hot water.
You’ll need somewhere outside your home where a unit can fit to a wall or on the ground. It must have some space around it to allow a good flow of air.

If you’re not limited by space inside your home, it may be worth the extra cost of installing a split system. Your installer should be able to talk you through your options and help you choose the design that works best for you.
Compact heat pumps are specifically designed to heat small, well-insulated modern flats and homes. These only need a cupboard with around 80cm x 80cm floor space in the flat, and this should be near an exterior wall.

Another potential option is an air-to-air heat pump. These are more often used to heat smaller properties such as park homes or flats. Other solutions are only suitable if you’re in a flat with shared services where each flat has access to communal heating.

How much does an air source heat pump cost to install?

The typical cost of installing an air source heat pump is around £11,000.

The cost of installation varies depending on:

the size of heat pump
the size of your property
whether it’s a newbuild or an existing property
whether you need to upgrade your radiators

What funding is available for air source heat pumps?

If you live in England and Wales, you can get £7,500 towards an air source heat pump with the Boiler Upgrade Scheme.

For Scotland, you might be able to get an interest-free loan or a grant to make your home more energy efficient.

If you live in Northern Ireland, there isn’t a specific grant currently available but you can still ‘get heat pump ready’ and apply for funding for insulation via NI Energy Advice.

Will I save money on my energy bills with an air source heat pump?

Heat pump running costs can vary depending on:

Whether your radiators are appropriately sized.
Your electricity tariff.
How the heat pump is controlled.

How much you could save on your energy bills also depends on what heating system you’re replacing.

At the moment, they generally cost slightly more to run compared to new gas and oil boilers.

This is because electricity is around four times more expensive than gas or oil.

But, because heat pumps are so much more efficient, as electricity prices change over time, we expect to see these savings improve. And if you’re replacing any other kind of heating system, you should see savings on your energy bills.

Here are the potential annual savings of installing a standard air source heat pump, including any recommended radiator upgrades, in an average sized, three-bedroom semi-detached home.

England, Scotland and Wales

Northern Ireland

How do I get an air source heat pump?

Decide whether an air source heat pump is right for you

Use our free online assessment tool – GoRenewable – to help you work out what kind of heating system is best for you.

Most heat pump installations are considered ‘permitted developments’, meaning you don’t need planning permission.

However, there are exceptions, and it’s best to check with your local planning department. This is especially important if you live in a listed building or conservation area.

Find a trusted installer

Get quotes from certified installers who are both accredited through the Microgeneration Certification Scheme (MCS). We recommend getting quotes from at least three different installers to make sure you’re getting the best value for money.

Find out more about finding a reputable installer for your air source heat pump.

Get your heat pump

We’ve got a step-by-step guide that takes you through the whole heat pump installation process, from finding funding all the way to ongoing heat pump maintenance.