What is an Air Source Heat Pump?

air source heat pumps

By 8 min read


An air source heat pump will save you £255 per year, on average

They’ll work at temperatures as low as -15°C

They can cut your carbon footprint by at least 2.5 tonnes of CO2 per year


Climate change means that gas boilers are going the way of coal and the dinosaurs – but for you, that may be a positive change.

Renewable ways of producing energy – like air source heat pumps – don’t just save the planet; they also save you money.

These machines are set to become a common feature of homes – and why not, when they can pluck heat from the air and turn it into a clean, unlimited source of energy for you and your loved ones.

After all, if you can produce energy from the sun, the wind, the ground, and the sea, why not the air?

infographic explaining how an air source heat pump works

What is an air source heat pump?

An air source heat pump is a machine that takes air from outside, and uses it to run your home’s heating and hot water systems.

You can think of it as the opposite of an air conditioner, which takes hot air from inside your home, cools some of it, and directs the rest outside.

An air source heat pump absorbs outside heat and converts it into a fluid, before heating it with a compressor, then directing that water to your home’s heating and hot water networks.

air source heat pumps

The pump sits outside your home, extracting heat from the air even when the mercury falls as low as -15°C, according to the Energy Saving Trust.

It runs on electricity, but produces more in heat energy than it consumes in electrical energy, meaning it’s more efficient than most heating systems.

And what’s more, it’s possible to make an air source heat pump completely renewable.

The heat in air is an unlimited resource, so if your electricity is fuelled by renewable energy, your system will be as green as a freshly manicured lawn.

Are air source heat pumps popular?

These machines are becoming increasingly popular – and for good reason.

Gas boilers are set to be banned in newly built houses from 2023, meaning people across the UK need another way of heating their homes.

Mike Childs, head of science at Friends of the Earth, told The Guardian in July 2021 that for most parts of the country, air source heat pumps were the best option for heating people’s homes in light of this news.

The government has also set a goal to install 600,000 heat pumps per year by 2028, showing how central this heating method is to its plans for an eco-friendly future.

For context, a total of 239,000 heat pumps had been installed in the UK, as of 2019.

As we move towards a time when the UK is responsible for net-zero carbon emissions, you can future-proof your home by getting a potentially 100% renewable source of electricity – all while cutting your energy bills.

And it’s not just in the UK. The number of households buying air source heat pumps in North America, Europe, and northern Asia is set to triple by 2025, according to the International Energy Agency.

By 2030, 22% of homes in these regions will have air source heat pumps.

Can you get paid for having an air source heat pump?

Yes, the government will pay you for using an air source heat pump.

Just apply for the Renewable Heat Incentive (RHI), and you could receive quarterly payments for seven years, based on the amount of electricity you’re estimated to be producing.

The current RHI tariff is a hefty 10.92p per kWh.

That’s an excellent return when you consider that the Smart Export Guarantee pays solar panel owners just 5.57p per kWh – at most – and the average price for a kWh on the National Grid is 17.2p per kWh.

What are they connected to?

Your air source heat pump will sit just outside your property, connected to a heat pump cylinder inside that circulates the pump’s hot water and stores excess water for later.

The pump will also need to be connected to a source of electricity.

women appreciating a heated home

How are air source heat pumps installed?

The first step is to hire a qualified installer, as this is a job that’s worth leaving to a specialist.

They will assess your property and find an appropriate place outside to put the air source heat pump, where it has all the space it needs to constantly access a good flow of air.

The unit will either be fitted to the wall or placed on a flat surface, meaning your installer won’t need to dig up any of your property.

All they’ll need to do then is plug it into the mains, and connect the necessary pipes and cables from the unit to the heating network inside your home.

This will involve connecting the air source heat pump to your radiators, and underfloor heating system, if you have one.

Your installer will then set you up with at least one control panel or thermostat inside your home, so you can check and alter the way your pump is running.

The entire process should take between one and two days, depending on the size of your home.

What are the pros and cons of air source heat pumps?

Pros
Cons
You can get paid for the energy you produce through the government’s Renewable Heat IncentiveIt costs £6,000 to £8,000 to buy and install
You’ll save £255 per year, compared to an old gas boiler
You’ll cut at least 2.5 tonnes of CO2 from your carbon footprint
You’ll be future-proofed against government efforts to reach net-zero emissions

Air source heat pumps vs gas boilers

The rise in popularity of air source heat pumps is partly due to a large majority of Brits wanting to fight climate change, and partly because the government is set to ban gas boilers in newly built homes from 2023.

Many see air source heat pumps as the natural successor to polluting gas boilers – and it’s easy to see why.

New boilers are all at least 92% efficient, but air source heat pumps blow this figure out of the water, with a typical efficiency rate of around 350%.

This is because air source heat pumps produce between three to four units of heat energy for every unit of electrical energy they use, thanks to water holding onto more heat than air.

So while a heat pump will cost you more upfront, its gloriously high efficiency rate makes up for this fact, by saving you more money in the long run.

Replacing your old gas boiler with an air source heat pump will typically save you £255 per year, according to the Energy Saving Trust, as well as a massive 5.2 tonnes of CO2.

When you consider that the average person in the UK is responsible for 6.5 tonnes of CO2 per year, that’s an incredible reduction to your carbon footprint.

And even if you have a brand new gas boiler, you’ll still cut your annual CO2 emissions by 2.5 tonnes, on average.

Do you need planning permission to install an air source heat pump?

You won’t automatically need planning permission for an air source heat pump, according to the government’s Planning Portal site.

However, if you already have an air source heat pump or wind turbine installed at your property – or if you live in a listed building – you’ll need planning permission.

And even if that doesn’t apply to you, there are naturally still some rules to follow.

Ask your installer if your unit complies with the following regulations, and check with your local council as well, to make sure.

The pump must:

  • Be certified by the Microgeneration Certification Scheme (MCS)
  • Be at least one metre away from your property’s boundary, or if you’re installing it on a flat roof, one metre from the edge of the roof
  • Have a minimal effect on the appearance of the property
  • Be used for heating purposes only

The external unit must also be equal to or less than 0.6m³, and produce a noise that doesn’t exceed 42 decibels – but don’t worry, your MCS-certified installer has to take care of this.

Heat pumps as air conditioners

An air source heat pump normally works like an air conditioner in reverse, using warmth from the outside to heat the inside of your home – but sometimes you can switch it around so it acts exactly like its cooler cousin.

If that sounds like an attractive option, make sure you opt for a heat pump with a dual option.

Just like an air conditioner, these dual option heat pump models take warm air from your home and release it outside.

They also cool some of this hot air, and release the resultant chilled breeze into your living space – making sweltering summer days a bit more bearable.

Next steps

You’re ready. You have all the knowledge you need, right at your fingertips, and you’re fully prepared to save money and CO2 by purchasing a new air source heat pump.

Find the model you want, an MCS-certified installer to put it in place, and before you know it, you’ll be making your wallet and the Earth a better place.

Josh Jackman Senior Writer

Josh has written about eco-friendly home improvements and climate change for the past three years. His work has featured on the front page of the Financial Times; he’s been interviewed by BBC Radio; and he was the resident expert in BT’s smart home tech initiative.