How air source heat pumps are revolutionising heating in the UK. (2024)

Here in the UK, there’s a big change happening in the way we heat our homes. The last few years have seen a substantial rise in the number of homeowners opting to install a heat pump over a traditional boiler.

Every household that does is helping to reduce their carbon footprint, as well as helping the UK on its path to a more sustainable future. It can have a positive effect on energy bills too. Replacing an old G-rated gas boiler with an energy efficient heat pump could save the bill payer around £340 a year.¹

From the speedy way they’ve come to the fore, you could be forgiven for thinking heat pumps are new – when in fact, they’ve been around since the 1940s. Now, heat pumps look set to become an ever more frequent sight, thanks to the government’s ambitious target to install a further 600,000 a year by 2028.² While both ground and air source heat pumps (ASHPs) are increasing in popularity, ASHPs are becoming the UK favourite, being both cheaper and easier to install in most cases. Let’s dive into just why they’re revolutionising UK home heating.

What are air source heat pumps?

Put simply, an heat pump is a renewable heating system that extracts heat from the air outside your home, then uses it to warm the inside. It heats your hot water too, and works rather like a fridge, only in reverse. While a fridge extracts heat from the food inside it then pumps it out into the room, an ASHP extracts heat from the air outside and pumps it into your home.

The process still requires electricity. But the heat energy it produces far exceeds the electrical energy that’s used to make it. This means an heat pump is a more energy-efficient way to heat your home than a traditional gas or oil boiler. Even better, it produces far fewer carbon emissions than other heating systems. Heat pumps produce around 850 kg of CO2 per year, compared with gas boilers which produce about 2,500 kg of CO2.³

How do heat pumps work?

Heat pumps work through the use of a refrigerant – a chemical that can change its state from liquid to gas and back again. This is pumped around a closed loop of pipes, known as the refrigerant circuit, which is made up of an outdoor and an indoor unit.

The refrigerant starts off as a liquid, and as it passes through the outdoor unit, it absorbs heat from the air. Then it travels into the indoor unit, where it releases its heat inside your home. From there, the refrigerant travels back to the outdoor unit, where the cycle begins again.

Common misconceptions about heat pumps.

• Heat pumps won’t work in cold weather.Wrong. Heat pumps create heat using the outside air, in the same way that the air conditioning in a car can provide heat when it's cold. It can pull heat from air when the temperature is as low as -27°C. (Fun fact – there are more heat pumps in colder European countries like Norway and Finland than anywhere else in the continent⁴, so the relatively mild UK climate is more than adequate.)

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• Heat pumps don't provide hot water.Not true. Heat pumps use an insulated hot water cylinder to heat and store your water. It stays hot for hours, so you should always have plenty for running a bath and washing the dishes.

• Heat pumps are noisy.Wrong again. The noise they create is similar to an extractor fan – around 50-60dB. This can be minimised using rubber dampers, and the sound isn’t constant because the pump only runs when it’s producing extra heat or hot water.

• Heat pumps need a lot of servicing.In line with the manufacturer’s guidance and our own advice, a qualified heat pump engineer should service your heat pump once a year. In other words, just like a typical gas boiler.

• How easy is it to install an air source heat pump?Fitting one is a pretty straightforward process, and only takes a day or two. The indoor unit is usually mounted on a wall, while the outdoor unit can be mounted on either a wall, the ground, or a rooftop in the case of some flats. A refrigerant circuit then connects the two.

What's the cost of installing a heat pump?

The cost of an ASHP can vary depending on a number of factors:

• The size of the heat pump.

• The size of your property.

• Whether it’s an old property or a new-build.

• Whether the property requires modifications like improved insulation, new radiators or underfloor heating for optimum performance.

An average heat pump installation typically costs between £10,000 and £20,000 (based on a three bedroom semi-detached home). That said, grants are available that can make a big difference to the cost. The government’s Boiler Upgrade Scheme could save you £7,500 off the cost of a new ASHP. It’s all part of £3.9 billion of funding in the Heat and Buildings Strategy, aimed at helping homeowners to cut their carbon emissions – and the UK to reach its target of net zero by 2050.All in all, an air source heat pump is a highly efficient, environmentally friendly way to heat your home and water, and it could help to reduce your energy bills. They’re relatively easy to install and maintain, and if you’re looking for a new heating system, it’s a great option to consider.