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What is an air source heat pump and how do they work?

An air source heat pump mounted outside of the home

If you’ve done any research, you may have spotted that the UK Government is offering grants up to £7,500 to install an energy efficient air source heat pump for your home.

If you’re looking to take advantage of this funding, it’s useful to know what an air source heat pump is and how it works, and that’s where we come in.

To help get you up to speed, we’ve gathered all the information you need to make a measured decision on whether an air source heat pump could be beneficial for your home.

We’ll go through everything from how a heat pump works, the pros and cons, and all the questions you might have before choosing your next heating system.


Table of contents

  1. What is an air source heat pump?
  2. How does an air source heat pump work?
  3. Air source heat pump advantages and disadvantages
  4. Common questions about air source heat pumps
  5. More help from HomeServe

What is an air source heat pump?

Heat pumps use heat energy from the environment to produce heating and hot water for your home. There are three types of heat pump that all work in the exact same way as an green way of generating energy:

  • Air source heat pumps
  • Ground source heat pumps
  • Water source heat pumps

in this guide we’re concentrating on air source heat pumps, which means the heat energy generated from the air produces heat and hot water.

How does an air source heat pump work?

Air source heat pumps work by transferring heat energy generated from air outside to heat your water, which is then used to heat your home using the following four steps.

A diagram of a the four step process of an air source heat pump

4 step cycle of a heat pump

  1. Air is carried from outside to a heat exchanger that sits within the pump, this exchanger contains a fluid known as a refrigerant which is capable of changing at low temperatures.
  2. Using electricity, this gas is transferred to a compressor which increases the pressure of the gas. As the pressure of the gas increases, so does its temperature.
  3. As the hot gas reaches the heat exchanger, the heat produced is extracted from the air and used for heating your home and hot water.
  4. This cycle is then completed and begins again to ensure that your home continues to have heating and hot water

Air source heat pump advantages and disadvantages

If you’re considering installing a heat pump into your home, you may want to consider the pros and cons before delving into the market.

5 advantages of an air source heat pump

1) Reduce your carbon footprint and support the environment

Heat pumps can be more efficient compared to traditional boilers. By using cleaner electricity they will help reduce your home’s carbon footprint.

In principle a heat pump should use around a quarter of the energy needed to run a traditional gas boiler, but this can depend on the temperature of the air outside and how much electricity is needed to heat it to the required temperature.

2) Air source heat pumps are more efficient than gas boilers

The average heat pump is three to four times more efficient than an average gas boiler. Heat pumps typically have an efficiency rate of 300%, meaning that on average, your heat pump will produce three units of energy for every unit of electricity it absorbs at 7oc ambient air temperature and with a 35oc flow temperature..

This efficiency makes heat pumps kinder to the environment than gas boilers and could help reduce your energy bills.

3) Reduce your energy bills

Because heat pumps use electricity more efficiently, and with the ever-changing prices of gas and oil, installing an air source heat pump could see you use less energy, which can help lower your energy bills.

4) No VAT to pay on installation

The government has recently announced 0% VAT on the installation of heat pumps and biomass boilers, which is in place until 2027. This will help towards reducing the cost of your installation.

5) Get ahead of the curve

Heat pumps are seen as an important part of the future of heating, and installing an air source heat pump will give you access to the latest technology and help you future-proof your home.

4 disadvantages of an air source heat pump

1) Expensive to install

The first thing to consider when you’re thinking of installing a heat pump is that they can be a little pricey.

Typically you’re looking at around £7,000 to £11,000 for a standard model, which can go up to in excess of £20,000 for more advanced models. So, even with the help of government funding you could be looking at a high cost.

2) Can be costly to run

Though they can reduce your energy bills, the running costs of heat pumps can vary depending on things like the size of your home or how well insulated your home is.

Running costs in the winter can be higher too. This is why insulation is essential when it comes to overall efficiency. The better your insulation, the more you’ll get out of your heat pump.

You might find our guide on insulating your home a useful read to understand how you can prepare your home.

The size of your radiators are a factor, too. If you have smaller radiators in your home, a heat pump may struggle to heat the room as they work at a lower temperature than a gas boiler. This could lead to increased costs as you may keep your heating on for longer periods to get your living space to the right temperature.

3) Not suitable for all properties

For the best performance, heat pumps usually work best with underfloor heating or warm air heating or coupled with large radiators.

They can also take up a lot of space, so if you don’t have external space for a fan unit then a heat pump may not be compatible with your home, so it’s worth taking this into consideration.

4) They can be noisy

As heat pumps use a fan system they can be quite noisy, much like an air conditioning unit. You can find some units that are known as “whisper quiet” systems which virtually have no noise at all, but they are towards the top end of the cost bracket.

5) Air source heat pumps work at a lower temperature

As heat pumps generally heat the water in your home to around 55 degrees, which is lower than a gas boiler (typically 75 degrees), it may take longer for your home to heat up to your desired temperature.

If you have larger radiators installed or a radiator with a double or triple panel, this can improve heat circulation and help you get the most out of your heat pump.

Common questions about air source heat pumps

So now you know what air source heat pumps are, how they work and the pros and cons. But you’ve no doubt still got questions, so we’ve covered the most commonly asked questions here, before you go and do a bit more research on your own.

Is an air source heat pump easy to use?

Like with most modern technology, you’ll find that the operational side can be quite technical, but the controls can be very user friendly and you’ll find them very easy to operate.

Do I need to service my air source heat pump?

For your heat pump to work to its full potential you’ll need to get it serviced by a fully qualified professional every 2 to 3 years.

Is an air source heat pump cheaper than gas?

We’ve touched upon this above, but it’s worth explaining that the price of oil and gas over the last few years has fluctuated in value so electricity prices do seem like the steadier option.

However, it’s worth noting that heat pumps work more effectively with larger radiators and underfloor heating, which can obviously see the price of usage creep up significantly unless you’ve got access to solar or wind power.

We’ve got a really useful article titled Is gas cheaper than electricity, which should give you a bit of an insight of what you might be dealing with.

Will an air source heat pump keep my house warm?

Again, this will completely depend on your home and the level of insulation you have. If you have the right kind of insulation then a heat pump can be as effective as any other heating system.

More help from HomeServe

We know the importance of keeping a home cosy, and we like to make it our business to help where we can to do just that.

In this case, we appreciate that installing a heating system of any kind can be a costly affair – particularly when it comes to air source heat pumps.

So while you’re thinking about your next steps, we’d like to offer some energy saving tips for the home to help you lower the costs of your energy bills.

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About the author


Martin has more than 30 years experience within the gas industry and has worked for the regulator, CORGI, before moving into the private sector in 2009 to oversee gas compliance matters on the Government’s flagship energy scheme, Warm Front.

Martin is recognised in the gas industry with an Incorporated Engineer status (IEng); Martin is currently a member of the Gas Utilisation Committee with the Institutions of Gas Engineers and Managers (IGEM) and assist the gas industry by sitting on a number of committees which develop safety standards and guidance.

Martin is a fully qualified gas incident investigator and has a proven track record of competence through the national Accredited Certification Scheme (ACS) in domestic, non-domestic and Liquefied Petroleum Gas (LPG) gas installations.

Martin has been employed by HomeServe Membership Ltd since 2014 and currently holds the position of Head of Technical Governance.

Qualifications

  • Gas qualified in Domestic, Non-Domestic and LPG installations
  • Qualified Gas Incident Investigator – IGEM/G/L/8
  • BTEC Higher National Certificate Building/Construction Studies
  • LCL Level 3 Award in Initial Verification, Periodic Inspection, Testing Condition Reporting and Certification of Electrical Installations
  • City & Guild 6032 Advanced Craft Certificate Plumbing
  • Water Regulations

Years qualified

30+
Read more

Share this post

About the author


Martin has more than 30 years experience within the gas industry and has worked for the regulator, CORGI, before moving into the private sector in 2009 to oversee gas compliance matters on the Government’s flagship energy scheme, Warm Front.

Martin is recognised in the gas industry with an Incorporated Engineer status (IEng); Martin is currently a member of the Gas Utilisation Committee with the Institutions of Gas Engineers and Managers (IGEM) and assist the gas industry by sitting on a number of committees which develop safety standards and guidance.

Martin is a fully qualified gas incident investigator and has a proven track record of competence through the national Accredited Certification Scheme (ACS) in domestic, non-domestic and Liquefied Petroleum Gas (LPG) gas installations.

Martin has been employed by HomeServe Membership Ltd since 2014 and currently holds the position of Head of Technical Governance.

Qualifications

  • Gas qualified in Domestic, Non-Domestic and LPG installations
  • Qualified Gas Incident Investigator – IGEM/G/L/8
  • BTEC Higher National Certificate Building/Construction Studies
  • LCL Level 3 Award in Initial Verification, Periodic Inspection, Testing Condition Reporting and Certification of Electrical Installations
  • City & Guild 6032 Advanced Craft Certificate Plumbing
  • Water Regulations

Years qualified

30+
Read more

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