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Air Source Heat Pumps: The Complete Guide

Adam Cherry
By: Adam Cherry
Updated: 25th April 2022

Air source heat pumps are renewable heating systems that extract heat from the air outside to provide homes with heating and hot water. Replacing your current heating system with a heat pump could save you a considerable amount on your energy bills.

This guide reveals how air source heat pumps work, their benefits and the potential costs to see if it's the right heating system for you.

What is an air source heat pump?

Harnessing energy from the wind is well known, however, wind turbines aren't the only way we can harness energy from the air outside. Rather than generating energy from the wind, air source heat pumps extract heat from the air, even in temperatures as low as -25°C for some models.

To generate heat from the air, the air source heat pump, which is installed outside, includes a fan that rotates to bring the air inside. Following this, the air passes over a refrigerant fluid which is contained within an exchanger coil, the fluid then boils and evaporates, turning into vapour. Finally, this vapour is compressed at a high temperature to produce heat for central heating and domestic hot water.

The process an air source heat pump follows to produce heat and hot water is similar to a fridge or air conditioning unit but in reverse.

There are two types of air source heat pump: air-to-air heat pumps and air-to-water heat pumps. You will need to compare these in order to find the most suitable renewable heating system for your property.

An air-to-air heat pump will circulate hot or cool air around your home using fans. This is much like an air conditioning system but with the added ability to heat the property too. Air-to-water heat pumps on the other hand generate hot water that can be circulated to a wet central heating system, underfloor heating or hot water storage cylinder.

Advantages of air source heat pumps

Air source heat pumps are a renewable alternative to the traditional gas boiler. By harnessing energy from the air outside, they have many advantages over the use of fossil fuels.

Following the installation of an air source heat pump your home will benefit from lower energy bills, a reduced carbon footprint and the potential to receive government grant payments.

Let's take a look at the advantages of air source heat pumps in more depth.

No carbon emissions

One of the biggest advantages that renewable heating systems, such as air source heat pumps, have over gas and oil boilers is the reduced carbon footprint. Gas and oil boilers burn fossil fuels to generate heat and hot water, a process that produces carbon that's emitted into the atmosphere – a leading cause of climate change. Air source heat pumps, on the other hand, harness energy from a sustainable source and don't emit any carbon into the atmosphere whatsoever. Additionally, the air is a fuel source that will never run dry, unlike gas and oil, sources of which are running low.

Highly efficient performance will help to lower your energy bills

A modern condensing boiler will operate at efficiency levels of around 94%. This means the unit doesn't convert all of the fuel into usable energy as there is always some waste – which is emitted out through the flue pipe. Air source heat pumps, however, perform at efficiency levels in the region of 300% to 400%.

As a result of being so efficient, an air source heat pump could help to lower your energy bills. Depending on the type of heating system you have at the moment, you could potentially be saving as much as £900 each year.

Government funding

In recent years the Government has been working on different grants and schemes to encourage homeowners to convert to renewable heating systems. With an aim to reduce carbon emissions, these schemes are based on homeowners replacing fossil fuel systems with energy efficient, low-carbon alternatives.

You can find out more about the latest available grants in our grants and schemes section.

Still generate heat during the winter

It can be easy to think that an air source heat pump will only be able to heat your home during the summer months. However, air source heat pumps can actually continue extracting heat from the air during the winter.

When it gets too hot in the summer months, an air-to-air heat pump will be able to cool the property too.

Will last longer than a boiler

An air source heat pump can go on heating your home for as long as 20 – 25 years in some cases before it will need replacing. This is around double the amount of time that you should consider a boiler replacement. So, while the initial investment is higher than a gas boiler, you won't have to worry about a replacement for much longer.

Disadvantages of air source heat pumps

Air source heat pump disadvantages need to be considered despite their many advantages. The key consideration to make is whether your property is suited to an air source heat pump.

Air source heat pumps warm water to lower temperatures than boilers, which makes them better suited to heating systems with large radiators and underfloor heating. The larger surface areas will ensure that rooms are heated effectively. It does mean, however, that you need to ensure your property is insulated sufficiently so that this lower-level heat is prevented from escaping.

Even if your property is well insulated and has a suitable heating system, you'll need to find out whether the installation is even possible.

Installation of an air source heat pump can be difficult, so get the advice of a professional installer.

An outdoor area, such as a garden, is essential for air source heat pumps. While the pump itself won't take up much room, it needs plenty of space so that it can bring in the air. In terms of location, a sunny spot will be most beneficial as the heat pump won't have to work so hard to heat the air.

Finally, there's the cost. Air source heat pumps can be expensive, particularly when compared to gas boilers. Plus, if you have an A-rated condensing boiler then a heat pump will likely cost more to run too. Having said this, that investment could be heating your home for as long as 25 years.

Weigh up the pros and cons of air source heat pumps in Air Source Heat Pumps: Advantages & Disadvantages.

Best air source heat pumps

There's an ever-growing number of air source heat pump manufacturers which makes it more important to compare them to find the best air source heat pump.

Finding the best air source heat pump depends on the demands of your property. So it's worth looking at the specifications of multiple models before deciding on which to have installed.

When making comparisons, you'll need to decide between an air-to-air or air-to-water model. Also make a note of the output, efficiency, operating temperatures and price.

Air-to-Air Water Pump Models Available Output Ratings (kW) Efficiency Rating Lowest Operating Temperature
Daikin Altherma 3 4, 6, 8 A++ -25°C
Nibe F2040 8, 12, 16 A+++ -20°C
Samsung EHS Mono 16 A+++ -25°C
Vaillant aroTHERM Plus 3.5, 5, 7, 10, 12 A++ -25°C
Viessmann Vitocal 200-A 2.6 – 11 A+++ -10°C
Grant Aerona3 6 – 16 A++ -20°C
Mitsubishi Ecodan QUHZ 4.5 A++ -15°C
LG Therma V R32 5 – 16 A++ -25°C
Hitachi Yutaki S802 11, 14, 16 A+++ -20°C

Read more about these models in Best Air Source Heat Pump Manufacturers.

Cost of air source heat pumps

The cost of an air source heat pump may seem overwhelming, but the advantages make them a worthwhile investment.

The average cost of an air source heat pump installation falls between £4,000 and £11,000.

In terms of the best air source heat pumps, the potential costs range from £1,750 up to £9,000. Note that not all of these potential costs take into account the installation.

Best Air Source Heat Pumps Potential Cost
Daikin Altherma 3 £6,000 – £8,000
Nibe F2040 £6,000 – £8,500
Samsung EHS Mono £1,750 – £4,000
Vaillant aroTHERM Plus £7,000 – £7,500
Viessmann Vitocal 200-A £5,500 – £9,000
Grant Aerona3 £4,000 – £7,000
Mitsubishi Ecodan QUHZ £4,000 – £6,000
LG Therma V R32 £4,000 – £6,000
Hitachi Yutaki S802 £4,000 – £6,000

These costs are lower than ground source heat pumps and you can compare the two types of heat pump in Air Source Heat Pumps vs Ground Source Heat Pumps.

Air source heat pump installation rates will vary from installer to installer so it's worth comparing multiple quotes. By completing our simple online form, you can get free quotes from up to 3 installers based in your local area.

Air source heat pump running costs

By installing an air source heat pump, you could potentially be saving as much as £900 on your energy bills (this is if you're currently heating your home with an electric storage heater). In comparison, if you have a new A-rated condensing gas or oil boiler then there's no rush to replace it with an air source heat pump any time soon if you're looking to save money on your energy bills.

The table below shows your potential energy bill savings depending on the type of heating system in your home.

Current Heating System Possible Annual Energy Savings
G-rated Gas Boiler £400 – £465
New A-rated Gas Boiler Increase by £35 – £55
Old G-rated Oil Boiler £460 – £545
New A-rated Oil Boiler Increase by £45 – £55
Old Electric Storage Heater £800 – £900
New Electric Storage Heater £465 – £545
Coal £425 – £525

To extract heat from the air outside and convert it into usable energy, air source heat pumps need electricity. Electricity is one of the most expensive fuels, particularly when you compare it to gas and oil.

Air source heat pump installation

Unlike boiler installations, an air source heat pump doesn't have to be installed by someone with a certain qualification. Your installer should, however, talk you through everything that will be involved in the installation ahead of time.

The installation should go as follows:

    Ahead of the installation, the installer will carry out a survey of your property. At this time they will assess whether an air source heat pump will be able to effectively heat your home. This means having large radiators or underfloor heating as well as sufficient insulation.
    Installation will begin with the fitting of the heat pump itself. This is the large outdoor unit that includes a fan that spins to pull the air inwards. It must be fitted in a spacious area where air can flow freely and run parallel to a wall to which it can be securely bolted onto.
    Once the heat pump has been installed in the garden area, the installer will then connect it with the central heating system and hot water cylinder. The level of work involved at this point will depend on how far the heat pump is from the hot water cylinder. This could involve drilling through walls so that the wiring and pipework can take the shortest possible route.

The installation of an air source heat pump can be completed within 2 days by a competent installer.

An air source heat pump is the most straightforward type of heat pump to install. The alternative is a ground source heat pump which will take longer as they require underground piping.

Get multiple quotes

Before hiring an air source heat pump installer, we highly recommend comparing quotes to find the most competitive price. At Boiler Guide, we have a network of renewable heating installers across the UK and we can connect you with those in your area. All you have to do is complete our simple online form, letting us know that you plan to have an air source heat pump installed. You'll then get free quotes from up to 3 installers for you to compare.

Is an air source heat pump right for your home?

There's no doubt that air source heat pumps have a huge role to play in the future of home heating. In the fight against climate change, we must drastically reduce our carbon emissions and 20% of all UK emissions come from home heating. Air source heat pumps don't release any carbon into the atmosphere which is in contrast to the gas and oil boilers currently used to heat the majority of homes.

However, replacing the more than 20 million boilers installed in UK homes with air source heat pumps wouldn't be simple. Even if you were to put the practicality and cost to one side, not all properties are suitable for an air source heat pump.

The best way to find out if your home is suitable for the installation of an air source heat pump is by getting the opinion of a fully-qualified engineer. Complete our simple online form today and we'll connect you with renewable heating installers near you.

Adam Cherry

About the author

Adam Cherry

Adam is our resident home heating expert. His experience and advice has helped millions of customers improve the efficiency of their homes and save money.

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