What are air source heat pumps?

Air source heat pumps provide homeowners with an alternative way to heat their homes by allowing you to generate your own electrical energy and offering the potential to save money on your energy bills.

We’ve put together this article to summarise what an air source pump is, how it works and how one could save you money.

What is an air source heat pump?

Put simply; an air source heat pump is a carbon-free method (if using a carbon-free electricity supply) of heating your home. The pump absorbs heat from the outside air. This air then heats your home and hot water. Air source heat pumps look similar to air conditioning systems and come in various sizes, which will determine how much heat it needs to generate for your household. Homes requiring more heat will need a bigger heat pump.

There are two types of air-source heat pumps, which work in different ways and are compatible with different types of home heating systems. These are Air-to-water heat pumps and air-to-air.

Here are the key features of these:

Air-to-water heat pumps

This type of pump feeds the heat taken from the outside air into the wet central heating system. If your home has large radiators or water underfloor heating, this could be a good option for you. This is because air to water heating systems produces heat at lower temperatures than a conventional gas boiler system. Therefore, for maximum efficiency, they need a large surface area in which to release the heat generated over a longer period.

Air to water heat pumps are the most common models in the UK.

Air-to-air heat pumps

An air-to-air heat pumps takes heat from the outside air and is fed into your home through fans. As long as you have a warm air circulation system, the heat will be able to spread around your home. However, these systems cannot create hot water.

In warmer months, an air-to-air system can also operate in reverse. This means you can use it as an air conditioning system to cool your home (although planning laws often restrict this).

The drawback of air to air heat pumps is that they are not eligible for the governments Renewable Heat Incentive payments. We will discuss this further under financial rewards and incentives.

How does an air source heat pump work?

An air-source heat pump takes heat from the air and absorbs it into a fluid. A compressor then boosts the heat to a higher temperature. This higher temperature air then converts into heat for your home and hot water. The heat the air pump generates is sent to your radiators and any underfloor heating. The rest is stored in your hot water cylinder for later use.

What does your home need to be suitable for an air source heat pump?

Outside space

If you are considering an air source heat pump, you’ll need to fit it somewhere outside, for example against a wall or placed on the ground. Wherever it’s installed, you’ll need plenty of space all around it to allow airflow. As air source heat pumps come in varying sizes and the size needed depends on your homes heat demands, this will determine the amount of space required for your home. You generally won’t need planning permission, although you will need to comply with planning laws.


To help reduce heat loss it’s important to make sure you have good home insulation before installing an air source heat pump. This is because heat generation from the air source heat pump is optimum when producing heat at a lower temperature than traditional boilers. Although most heat pumps can work in -15 degrees and lower conditions, they are the most energy-efficient at higher temperatures and perform better in well-insulated homes.

Existing heating system

Air source heat pumps work best with underfloor heating systems and warm air heating. This is because they are able to operate at low temperatures. If your home doesn’t currently have a central heating system installed, you will need one before an air source heat pump will be able to work.

It’s also a good idea to check that you don’t need planning permission to install the air source heat pump. In the case of listed buildings, you may need the permission of the local authority. You should also check if your heat pump meets the building regulations for your locality.

What are the benefits of an air source heat pump?

There are a number of benefits of installing an air source heat pump, including:

  • An air-source heat pump can save you money. Especially when compared directly to a full electric heating system. They can also save money in comparison to oil and gas boiler alternatives.
  • You could obtain an income from the UK Government Renewable Heat Incentive.
  • Installing a heat pump will help reduce carbon emissions. Unlike burning gas, LPG, oil or biomass. Air source heat pumps produce no carbon emissions on site.
  • No need for fuel deliveries.
  • You can use it to heat hot water as well as your home.
  • Simpler installation than alternative ground source heat pumps.
  • Some heat pumps can cool down your home in the summer in addition to heating it in the winter.

What are the disadvantages of an air source heat pump?

There are many advantages to installing an air source heat pump, but as with everything, there are some downsides too. Therefore, it is necessary to understand both the good and bad before making this important choice for your home:

  • They produce a lower heat supply compared to conventional heating systems like gas boilers or electric heating. This means you are likely to need larger radiators and underfloor heating.
  • They can take a while to reach the set temperature, meaning your house could be left cold in the mornings.
  • Your home needs to be very well insulated to get the high energy-saving benefits.
  • They are noisy – similar to an air conditioning unit running.
  • They can be expensive. The cost of installing an air source heat pump is typically between £3,000-£11,000.

What are the costs of an air source heat pump?

Installing an air source heat pump is more expensive than installing a more traditional gas or oil central heating system. Air source heat pumps vary in price, but typically you will find them between £3,000 and £11,000. This will depend on a few factors, such as brand and the heat output as you’ll want to make sure you select one that can adequately heat your home.

Upfront costs

In addition, you’ll also need to consider the cost of the installation of an air source heat pump by a professional. This could raise the costs by a few thousand pounds. Many people who choose to switch to an air source heat pump do so as part of home renovations or improvements.

For example, if you are installing new underfloor heating you will also need to factor that into the cost too. You’ll also potentially need to consider improving your home insulation. Air source heat pumps are not great at heating poorly insulated, draughty homes.

There is no denying the initial outlay of installing an air source heat pump is a big investment. However, it is one of the most efficient ways to heat your home. An air-source heat pump efficiency can be three or four times higher than a modern gas boiler or electric heating system. This means the actual running costs can could be lower than a typical household heating system.

Running costs

There are a couple of factors that can impact the running costs of an air source heat pump. These are:

  • Heat Demand – This is the volume of heating required to keep the home at the desired temperature.
  • Air source pump efficiency – This is the pumps ability to effectively heat the property while using as little electricity as possible. This is known as COP or Coefficient of Performance.

In addition, the price you pay per unit of electricity will also impact the total running cost of the air source heat pump. This is because the unit requires a small amount of electricity to actually work.

A typical air-source heat pump may cost around 4.7p per kWh to run.

Because all homes vary, as do their energy use patterns, it’s impossible to give an accurate cost representation. To work out the running costs, you need to be aware of the COP of your heat pump. The COP provides a rating based on the amount of heat generated from an air source heat pump for every kilowatt of electricity input. Essentially, the lower the COP, the better. This means you are using less electricity to generate the volume of heat you need for your property.

For example, for every 1kWh of electricity, an air source heat pump produces 3 kWh of heat. The average UK home uses 12,000 kWh of electricity per year.

12,000 kWh av. electricity consumption / 3kWh (pump heat production per unit of electricity) = 4,000 kWh of electricity.

At 4,000 kWh of electricity priced at £0.14 a unit, it will cost you around £560 in annual heating costs using an air source heat pump.

Are there any grants/financial incentives available?

Yes. In the UK, there is the Renewable Heat Incentive Scheme. The incentive was set up to encourage residential customers to switch to renewable heat technology in return for a financial incentive. There is also a grant scheme that can cover some or all of the cost of an air source pump installation.

In addition, once installed, you will receive quarterly payments for the renewable energy you produce over seven years.

To qualify for the Renewable Heat Incentive scheme, you’ll need to follow these rules:

  • You must be listed as a Microgeneration Certification Scheme (MCS) certified product.
  • Receive an MCS certificate.
  • With your application, you’ll need to provide an Energy Performance Certificate (EPC), which is less than 24 months old.
  • You’ll need to make your application within the first twelve months of your renewable heating system being switched on.

How much money are you likely to save with an air source heat pump?

Savings will vary depending on your energy use and what type of heating system you are comparing it to. The average running cost of running an air source heat pump in a standard three-bedroom, semi-detached house is around £560 per year as per our example above.

Depending on which energy supplier you compare it to it could save you between £300-£400 per annum compared to the average dual fuel tariff. This is before any of the government rewards.

What is involved with the installation of an air source heat pump?

Like any other heating system, an air source heat pump needs to be professionally installed by a trained professional.

Here is a brief overview of the process that a professional will follow to complete a new installation of an air source heat pump:


Before any work is carried out, your appointed installer will visit your home to inspect the property in order to specify the correct system for your home and assess the complexity of the installation. They will provide you with a report on what the install involves and the savings you will likely achieve by switching to an air source heat pump system.

The installation

For a qualified installer, air-source heat pumps are usually fairly straightforward to install. The air source heat pump will need to be installed outside your property at a location with good airflow. The heating pipes and electrical connections will need to flow between the unit and your property.

Your installer will then work inside your home to connect the new system to your radiators and other heating sources, such as underfloor heating. You may experience some minor disruption to your heating, and hot water as your old heating system will need to be disconnected in order to complete the installation. However, this is in most cases minimal, and many installations are complete within two days or less.

What maintenance is needed for an air source heat pump?

The good news here is that air source heat pumps require very little ongoing maintenance. Of course, the maintenance recommendations will vary from unit to unit, and the manufacturer will recommend full details of any servicing recommendations. However, in most cases, your engineer will recommend the following to keep an air source heat pump in good working order:

  • Regular cleaning of the filters.
  • Cleaning of coils and fans (as necessary).
  • Make sure there is no disruption to your airflow by garden debris, such as leaves and dust.
  • Clean fan blades – You’ll need to turn off the unit to do this.

Unlike many other heating systems, air-source heat pumps are unlikely to require replacement or repair of any major parts during their lifetime.

The manufacturer may recommend that you have a seasonal check. Usually, in the run-up to the winter months, this is to assess everything is in working order and spot any problems you wouldn’t be able to identify without extensive knowledge.

The majority of air source heat pumps come with a 5-10 year warranty and have a lifespan of 15 years.


Hi, I'm Rob and I run I initially started this project 5 years ago when I was looking to switch energy suppliers and found there wasn't a website that provided simple, data backed reviews on all the suppliers available. Since then, I spent have a lot of time (too much some may say!) looking at all publicly available data about each supplier and writing reviews using this information. These reviews are updated as regularly as possible and any data is backed up by a source where necessary. I have also started writing guides on various energy related topics which hopefully you will find useful. If you find any issues, please use our contact form to let us know.

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