Air source heat pumps explained

Air source heat pumps are a hot topic right now, and for good reason. They’re a fantastic bit of technology that can heat your home by taking heat from the air outside – even when it’s cold – and moving it indoors.

Unlike gas boilers that burn gas to produce heat, heat pumps use electricity to move heat from outside into your home. Think of them as a bit like a fridge, in reverse.

In this guide, we’ll dig into exactly how they work, installation costs, and how they could help you save on your energy bills.

What is an air source heat pump?

Let’s get into this in a bit more detail. An air source heat pump is a low-carbon heating and hot water system.

It works by drawing heat from the air outside – even in winter – boosting it to a higher temperature, and then using it to heat your radiators, underfloor heating, or hot water tank.

Because heat pumps transfer existing heat rather than generating it, and run on electricity not gas, they’re an efficient and more sustainable way to warm your home.

How do air source heat pumps work?

Just like a fridge, a heat pump has a circuit of pipes filled with refrigerant. This refrigerant has a very low evaporation point. So even on very cold days, down to -15⁰C, it absorbs warmth from outside and turns from a liquid to a gas.

This gas goes through a compressor, and as the pressure goes up, the gas warms up. If you can think back to those science lessons at school about the principles of liquids, solids and gases – it’s basically the same thing here.

The warmed refrigerant then flows through a heat exchanger, releasing its heat into your central heating system to heat your radiators, underfloor heating and hot water.

How much electricity do heat pumps use?

Air source heat pumps are powered by electricity, and the amount of electricity a heat pump uses depends on the size of your home and how well it’s insulated.

What’s true across the board, though, is that air source heat pumps are incredibly efficient. Their average efficiency rate is 300%. This means 1 kilowatt-hour (kWh) of electricity a heat pump uses provides c.3kWh of heat energy. While for gas boilers, 1 kWh of gas provides 0.95kWh of heat energy.

Source: The Eco Experts

What are the benefits of air source heat pumps?

Energy efficiency

Heat pumps are three to four times more efficient than traditional boilers, according to the Energy Saving Trust. What makes them so efficient is the way they work. Instead of turning electricity into heat, they transfer warmth from the air outside into your home. This means they can technically produce more heat than the electricity they consume.

Lower energy bills

By using the heat already in the air, heat pumps need less energy to heat your home than old-school methods like boilers, which can mean lower energy bills for you in the long run.

A greener way to heat your home

Air source heat pumps only use electricity to heat your home and water. So it’s a great way to cut your carbon footprint compared to a gas boiler, particularly if that electricity comes from renewables.

Low maintenance and long-life

Heat pumps have fewer parts than boilers, which means they’re generally easier to look after. And with proper care they can provide reliable heating and hot water for 20 years – sometimes more (source: Energy Saving Trust).

Grants and financing

Currently homes in England and Wales can get a government grant of £7,500 towards the cost of a heat pump, subject to meeting certain criteria. There are different grants available for households in Scotland.

What to consider before installing an air source heat pump

Have you considered all the costs?

Heat pumps can require a higher upfront investment than boilers, particularly when you include both the unit and installation. That said, there are government grants available – depending on eligibility. And over time, you’re likely to see bigger savings on your energy bills.

Do you have enough outdoor space?

You’ll need enough space outside for the unit to be set up safely and have good airflow around it. In England and Scotland, an air source heat pump needs to be at least one metre away from a boundary. And in Wales, it needs to be at least three metres away. This will allow the heat pump to work efficiently – getting enough airflow and keeping noise levels low.

Is your home well insulated?

A well-insulated home helps a heat pump work at its best, keeping warmth inside and energy use low.

Are you likely to need any home upgrades?

Some homes may need larger radiators or underfloor heating to get the most from a heat pump.

Do you live in area with planning restrictions?

Most types of homes don’t need planning permission to install a heat pump as it’s done under what’s known as permitted development. But if you live in a listed building or conservation area then it’s worth checking any planning requirements first.

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

If you’re using electric, oil or LPG heating, a heat pump can help to lower your bills straight away, because it uses energy far more efficiently. Exactly how much depends on things like your electricity tariff (some energy suppliers like British Gas have begun offering lower-rate tariffs specifically for heat pumps), and the size and age of your radiators.

If you have a gas boiler you can still make savings but the costs are closer right now. This is because electricity is currently more expensive than gas (you might have heard this called ‘the spark gap’), which counterbalances the savings made by your heat pump’s efficiency.

The good news is government grants and the lower electricity tariffs suppliers are bringing in for heat pumps are already helping. And if you can combine an air source heat pump with solar panels you can start making significant savings, as well as making your heating virtually carbon neutral.

Finally, you can also boost your savings by combining a heat pump with some of Hive’s smart heating devices.

What funding is available for air source heat pumps?

There are several schemes that can help make installing an air source heat pump more affordable.

Homeowners in England and Wales may be eligible for the government’s Boiler Upgrade Scheme, which offers a £7,500 grant towards costs and installation.

In Scotland, the Home Energy Scotland grant provides £7,500, with an extra £1,500 if you live in a rural area.

Low-income households may also qualify for support through the ECO4 scheme, which can cover the full cost of energy-efficient home upgrades.

For the most up-to-date details, eligibility criteria and advice on how to apply, the best place to start is the government website. Once you’ve checked this out, the good news is that in most cases your installer can apply for the grant for you.

Is an air source heat pump right for me?

If you’re looking for a greener, more efficient way to heat your home, an air source heat pump could be a great fit.

They work best in well-insulated homes that have radiators or underfloor heating. And the only non-negotiable is having a little bit of outdoor space for the actual unit to live.

Installation is a big investment. But for many households, the long-term savings on their energy bills and lower carbon footprint make it worthwhile.

Read more about Hive heat pumps and decide whether it’s the right choice for you.

Looking to install an air source heat pump?

With Hive, you’ll get expert advice, installation from our trusted specialists, and smart controls that help you get the most from your new system. Plus, we’ll guide you through available grants to make it more affordable.

Air source heat pumps explained: How do they work?