Air Source Heat Pumps – Compare Offers from Local Installers in the UK
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Last updated: 14 October 2021

Air Source Heat Pumps in the UK

What Are Air Source Heat Pumps?

Air Source Heat Pump

Air source heat pumps provide efficient heating and cooling solutions for your home in any climate. This type of heat pump is a low carbon technology that converts solar energy from the outside air into electricity, which is used for domestic heating.

Domestic air source heat pumps, in particular, are one of the most affordable and cost-efficient heating solutions among UK households. Check our extensive guide on the pros and cons of air source heat pumps.

In fact, of all heat pumps sold in the UK, air source heat pumps account for 87% of the market share. Going forward, they will also be an essential part of the UK's goal of reaching the Net Zero Target by 2050.

The International Energy Agency, in their latest special report, stresses that no new gas boilers should be sold after 2025 if Net Zero targets need to be achieved by 2050. Heat pumps are expected to be a better, low-carbon alternative to heating homes in the foreseeable future.

The total cost of installing an air source heat pump ranges from £8,000 to £18,000. These costs depend on many factors, including:

  • The size of your home
  • How well insulated your home is
  • The brand of the pump
  • The pump size
  • The performance/efficiency of the pump

Interested in purchasing an air source heat pump? GreenMatch provides you with up to four quotes from reliable suppliers. This service is free and without any obligation. Compare heat pumps today by filling in the form at the top of the page.

How Do Air Source Heat Pump Systems Work?

Air source heat pumps (also known as ASHPs) are a low carbon heating system that use the ambient air to heat up your home. They can be used for both hot water and space heating.

Heat from the outside air is gathered and absorbed into a loop with refrigerant fluid. After the heat is extracted from the air it passes through a compressor. The compressor does as it sounds; it compresses, which results in a higher temperature. 

Another important part of the air source heat pump is the heat exchanger, which transfers the heat through piping to the needed locations such as radiators, underfloor heating systems, hot water circuits, or air conditioners in the house.

AIR SOURCE HEAT PUMPS - How Do They Work?

What Types of Air Source Heat Pumps Are There?

There are two types of heat pumps:

The exact functionality depends on the heat pump type.

Air to air heat pumps generate energy by moving air from one place to another. This process requires electricity. During the warmer seasons, heat gets extracted from the inside, and this warm air will then be released outside, leaving the inside of the house cooler. In this case, the heat pump functions as an air conditioner.

During the cooler seasons, the pump takes air from the outside. The pump presses the air together, a process that heats the air. The warmer air will then be released inside the house through an air conditioner unit, warming up the home.

Air to air heat pumps only provide space heating. However, when combined with other heating systems, for example, a boiler, the produced heat can be used to heat water.

The interactive graphic below illustrates how the process works. You can click on each point to read about the steps in more detail:

1 1: An outdoor unit draws in heat from the ambient air with fans, and then blows it over a heat exchanger coil. 2 2: The heat is transferred to a cold coolant flowing in the coil. Due to its very low boiling point, the heat only turns the coolant into a slightly warm vapour. 3 3: The slightly warm coolant vapour passes through a compressor that increases its temperature and compresses it to a denser vapour. 4 4: This hot coolant vapour is then transferred to the indoor unit(s) through internal piping systems. 5 5: The indoor unit blows out the heat from the coolant to the indoor air with fans, thereby warming up the room. 6 6: Once the coolant has transferred some of its heat to the air, it cools back into a liquid. 7 7: The liquid coolant passes through an expansion valve, which forces it to let go of more of its heat and mix with air, thereby creating a liquid vapour mixture. 8 8: The cold liquid vapour coolant mixture is then circulated back to the outdoor unit, to be heated again.
A2A for Heating(with title)

Air to water heat pumps, on the other hand, can provide both space and water heating, making it the more versatile heat pump type. For this reason, it is also the more commonly used type of air source heat pump in the UK.

Both types work more or less the same manner, however, with air to water heat pumps the heat gets transported to the wet central heating system, such as radiators, underfloor heating, or showers.

It works based on hydronic technology and functions like a boiler when it is supposed to provide a home with heat and hot water.

The interactive graphic below illustrates how the process works. You can click on each point to read about the steps in more detail:

1 1: An outdoor unit takes in heat from the ambient air and transfers it to a coolant. 2 2: A compressor increases the temperature of the coolant further. 3 3: The coolant transfers the heat to a hot water reserve tank via a heat exchanger. 4 4: Hot water from the tank is circulated to radiators and faucets in the house. 5 5: Cold water is transported back to the water reserve tank. 6 6: The coolant is cooled by the water and transferred back to the outdoor unit to be heated again.
Air to Water Heat Pump

Air to Air vs Air to Water Heat Pump: A Comprehensive Comparison

With two air source types in the market, the question is which one is the best for your home energy needs. Both air source types extract heat from the outside air using an outdoor heat pump unit. Even though they may sound similar, they're essentially two completely different solutions for space and water heating needs

They both rely on electricity for the heat pump to run but are far better in efficiency compared to tradition heating systems. Air to air heat pumps are more commonly used as air conditioners, whereas air to water heat pumps are used for both space heating through radiators and underfloor heating, and also used for heating water. While air to air heat pumps are cheaper to install, they are a couple of downsides when compared to air to water heating systems.

The video below compares the two types by covering the 4 most important points:

  • Technology
  • Cost and installation
  • Efficiency
  • Savings
Air to Water VS Air to Air Heat Pump: A Comprehensive Comparison

What Are the Pros and Cons of an ASHP?

There are many pros and cons to air source heat pumps, and it's important to be aware of them before making an investment.

A summary of the advantages & disadvantages can be seen below:

Advantages
  • Reasonable capital costs
  • Easy installation process for both air to air and air to water systems
  • Low carbon heating system
  • High efficiency. With an average COP of 3.2, air source heat pumps perform well without wasting energy
  • Low running costs, meaning lower energy bills
  • Eligibility for the Renewable Heat Incentive scheme
Disadvantages
  • Condensed air can produce water that can freeze at low temperatures, interrupting the heat flow
  • The outdoor fan can be somewhat noisy
  • Lower maximum tap water temperature than with traditional heating systems

Many of the downsides above can be prevented by having professional installers plan and install the air source heat pump system. Keep in mind that you will need to take proper care of your heat pump to ensure that the efficiency stays up to par and the running costs remain low.

What Is the Cost of Air Source Heat Pumps?

Air source heat pump prices range between £1,500 to 18,000. This wide range in price is due to the fact that there are different types of air source heat pumps (air to air and air to water), many brands, and varying sizes, and performance strengths that all determine the price.

Air Source Heat Pump Costs
ASHP System Type Average Price
Air to water heat pump £8,000 - £18,000
Air to air heat pump £1,500 - £3,500

These prices are broad estimates based on the current market rates. For a more accurate price, you should always get quotes from multiple installers.

When you invest in a heat pump system, in this case, an air source heat pump, you have to take into account installation and possible home altering costs.

It is difficult to predict the air source heat pump installation and running costs. These will vary depending on many factors, like the size of your home, how well insulated it is, and what room temperature you are aiming to achieve.

An air source heat pump is both efficient and affordable. It is slightly more expensive than a condensing boiler, however, when it comes to heat pump types, air source heat pumps are less expensive than ground source heat pumps. The starting price of an air source heat pump is 50% cheaper than that of a ground source heat pump. Check our dedicated guide on ground source heat pump prices.

What Is the Installation Cost?

The installation cost of air source heat pumps varies depending on your current heating system.  If you need auxiliary work done, such new radiators fitted or underfloor heating installed, your installation costs will be higher. You can expect an additional £2,000 - £4,000 for this.

When you are given a quote, the full costs are usually included, such as labour costs and auxiliary works.

As air source heat pumps are easy to install, they are very common in the retrofit market. That being said, if you need to also have new radiators or pipework done before you can install an air source heat pump, then the installation costs will rise.

What Are the Running Costs?

The running costs of a heat pump depend on a number of factors:

  • the system size
  • the system's efficiency (SCOP)
  • the outside temperature
  • your energy expenditure 
  • how well insulated your home is
  • RHI tariffs

When it comes to the system itself, the size and efficiency will naturally play a huge part. The bigger the size, the more energy it will generate, and the more expensive it will be to run. The efficiency of the system is equally as important to consider. To read more about this, you can read our analysis of how much you can save depending on efficiency.

Air source heat pumps are said to be more efficient in warmer climates, however, this does not mean that they are not cost-effective in colder climates. An air source heat pump, just as a thermodynamic water heating system, can get heat from the air even when the temperature outside drops down to around -20°C,  though not as efficiently.

They generally start to function slightly worse in temperatures lower than 0°C. Fortunately, the UK winters typically do not drop far below 0°C.

Moreover, your home's insulation and your own energy needs will also impact the running costs. To begin with, your home should be well-insulated to get the most out of your heating system (out of any heating system, as a matter of fact). Additionally, how much heating you require will also determine how much you spend on your bills.

Finally, you can lower the running costs of your air source heat pump by taking advantage of the Renewable Heat Incentive.

Financing a Heat Pump System with a Grant

If you decide to buy an air source heat pump, you are eligible to receive some government support in the form of a grant. The specific grant you can apply for is the Renewable Heat Incentive (RHI). Keep in mind that in order to be eligible for this grant, the air source heat pump has to be an air-to-water heat pump.

This incentive was established April 9th, 2014 to help the UK government meet environmental goals and targets through the support of domestic consumers of renewable energy sources. If you are a homeowner, landlord, or home-builder you can apply for this incentive.

The following table breaks down the RHI tariff rates per heating system.

RHI Earnings
Heating System RHI Tariff
Air source heat pumps  10.92 p/kWh
Biomass boilers 7.01 p/kWh
Ground source heat pumps 21.92 p/kWh
Solar thermal 21.49 p/kWh

These tariffs were adjusted for Q1 2021/2022. More in-depth information can be found on the Ofgem website.

Another government incentive is the 5% VAT reduction on energy-saving products, which includes air source heat pumps. You need to be over 60 years of age and a recipient of income of disability benefits to qualify.

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How Much Can You Save with an ASHP?

If you purchase an air source heat pump you will be able to save energy as well as money. This is due to the efficiency levels at which air source heat pumps produce energy. You could save up to £1,335.

High Efficiency Means Saving Money

The efficiency of an air source heat pump is measured by the Coefficient of Performance (COP). This refers to the maximum efficiency with which the heat pump can run. Most air source heat pumps have a COP between 2 to 4, but in some cases, it can be as high as 5.

The COP refers to how many kilowatts of heat 1 kilowatt of electricity can produce. An air source heat pump with a COP of 4 will produce 4 kilowatts of heat. Meaning the heat pump will provide you with four times more heat than if you would heat your home using electricity.

Air Source Heat Pump COP and SCOP

If the temperatures outside of a house are around 7°C, the average air source heat pump will have a COP of 3.2. In most parts of the UK, the average temperature is between 5 - 8°C. This means an air source heat pump will generally perform quite well in the UK.

In order to save money, the efficiency of your green home solution is very important. Efficiency is one of the aspects that determines the running costs. Two other key players when it comes to running costs are:

  • The amount of heat needed in your home.
  • The temperature your source of energy can generate.

A Scenario: Running Costs Savings

In our example, we will look at how much energy is generally needed and used, and how much a household consisting of four people will spend on running costs. We will look at a detached house that is 200m2.

A house that is 200 m2 with an energy performance rating of 125 kW/ year/ m2, will most likely need around 25,000kWh for heating.

The running costs of an air source heat pump for a detached house, like the one from our main example, the running costs would be around £1,120 with the current electricity price of 14.37p kWh. Now compare this to your current energy bill.

The average running cost of a condensing boiler in a 200 m2 house, with an efficiency of 85%, is £1005. For a boiler it is £1615.

An average home in the UK is around 76 m2. Meaning that for most houses the running costs will most likely be lower than the ones from our example.

How Can I Prepare My Home for an ASHP?

Before you take the step of buying an air source heat pump, it would be smart to consider your current situation and the possibility of implementing changes.

How to prepare your house for a heat pump

Ensure There Is Adequate Space

The first factor you should think about is space. Air source heat pumps need some space for the outdoor module, which is placed either on a wall or directly on the ground. What is important, is that the system needs some space around it in order to create a good flow of air. Therefore, placing an air source heat pump near a sunny wall is preferable.

Have a Sufficient Level of Insulation

Secondly, you need to consider if your home is well insulated. Heat pumps will function better when a home is well insulated. It is important to add proper insulation and draught-proofing to the home to reach the highest level of efficiency for your air source heat pump.

Consider What Heating System You Are Switching From

Next, you need to think about the current energy source and the fuel it uses. If your home currently uses electricity or coal to fuel your heating system, an air source heat pump will pay for itself much quicker.

You might also want to think about the heating systems that are part of your home. Purchasing an air to water heat pump can be more beneficial if it's used with an underfloor heating system or warm air heating, because of the lower water temperatures needed.

Explore Potential Ways to Complement Your ASHP

Finally, you should think about options to complement the air source heat system. Combining an air source heat pump system with other building work could reduce the costs of installing the system. 

Combining an air source heat pump with other green home solutions will also greatly benefit you. 

A secondary system will be able to function as a backup or boost the performance of the heat pump. Although not necessary, you can combine an air source heat pump with a condensing boiler.

Alternatively, you could power your air source heat pump system with solar panels, thereby reducing your carbon footprint even further.

And, finally, you could also consider combining your heat pump with solar panel heating.

Ask Your Heat Pump Installer the Right Questions

It's important to find the right heat pump installer before you invest in an ASHP. There are a few questions you should always ask to ensure you are getting the right system and to ensure that the installer has the right qualifications.

Choosing a Heat Pump Installer - 5 Questions to Avoid Costly Mistakes

If you would like to compare heat pumps and receive free air source heat pump quotes, Greenmatch can help you get what you need. Just fill in the form at the top of this page and you will receive up to four quotes from our trusted suppliers. This service is completely free and non-binding.

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Attila Tamas Vekony
Written by Attila Tamas Vekony, UX Manager

Attila is the UX Manager at GreenMatch. He holds a degree in international business with four years of coordination experience in marketing, user experience, and content creation. Attila likes to write about solar energy, heating technology, environmental protection, and sustainability. His and his team's articles appeared in well-known sites such as The Conversation, Earth911, EcoWatch, and Gizmodo.