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Air source heat pumps

what is energy efficiency

This guide is intended to provide general guidance only. It is not intended to give you advice on your personal financial circumstances. You should seek independent professional advice if you’re unsure about anything mentioned in this guide or what choices to make.

Scientists and inventors are constantly trying to come up with greener ways to heat our homes. Boilers are getting more energy efficient almost every year – but they’re no longer necessarily the best way to run a central heating system.

Air heat pumps have moved the goal posts. They’re semi renewable and low maintenance, and they could cut your home heating costs.

But are they right for your home?

What is an air heat pump?

Air heat source pumps are a specific kind of central heating pump. They work rather like fridges or air-conditioning units, but the other way round: changing cold air into warm rather than the reverse.

The air heat pump is installed outside the building it needs to heat. If it’s your home, you’ll probably want the pump installed round the side or at the back, as they’re quite big and not very beautiful. A sunny spot is best, as then the pump doesn’t have to work so hard to warm up the air. That said, it can even absorb heat from the air at sub-zero temperatures, so it could still be suitable even if you’ve only got a very small and shady back yard.

The unit absorbs air into a fluid and compresses it, which raises its temperature. It then pumps the warm fluid into radiators, underfloor heating, or warm air convectors and hot water.

What are the benefits of an air heat pump?

  1. They could reduce the costs of heating your home, if you’re switching from an electric or coal-fired system
  2. They are very low maintenance,
  3. You don’t need any fuel deliveries
  4. They sit outside your home, so they could free up some space in your kitchen or utility room
  5. They’re great if you’re building a new property as they reduce the installation costs and you can make sure the building is well insulated and sealed from the start
  6. They’re relatively environmentally friendly and produce fewer carbon emissions than most boiler systems
  7. You can use them as air conditioning when it’s hot in summer
  8. You might be able to earn income through the government’s Renewable Heat Incentive (RHI) scheme
  9. An air-to-water system could heat both your home and your water – although this could reduce its overall efficiency

And what are the disadvantages?

  1. The pump works most effectively at lower temperatures, so they’re best with large radiators or underfloor heating
  2. They provide a lower heat than conventional systems, so your home would need to be very well insulated and draught proof
  3. They wouldn’t be suitable if you live in a flat with no outside space for the unit
  4. You may need to get planning permission for the installation

Are there different types of air heat pumps?

There are two different kinds of air heat pump: air-to-water and air-to-air.

  1. Air-to-water systems distribute heat by pumping liquid through pipes and radiators, or underfloor heating pipes
  2. Air-to-air systems produce warm air which is circulated around your home by a network of fans.

Air-to-water systems are most common, as they can be used for both heating and hot water, whereas air-to-air systems are unlikely to be able to heat water.

Why do you describe them as semi renewable?

In general, an air heat pump will be more environmentally friendly than whatever system you’re replacing, as the main component used to create heat is air – which is a renewable resource.

However, the unit does use some electricity to run the pump, which means it isn’t completely carbon neutral. That’s why, even though it uses electricity more efficiently than regular electric heating units, it only counts as semi renewable.

How much does an air heat pump cost?

Installing an air heat pump could cost between £7,000 and £11,000, according to the Energy Saving Trust. Make sure you get several quotes, and that you’re confident your installer has done similar work before and knows what they’re doing.

The running costs will depend on:

  1. The size of your home
  2. How old it is
  3. How well insulated it is
  4. How warm you want it to be
  5. Whether you have underfloor heating or radiators

What savings could I make?

Any savings you make will depend on what kind of fuel you’re replacing. If you’re using mains gas, for example, you probably won’t save much – so it would take many years to recoup the costs of installing your air heat pump.

However, it could work out cheaper than an electric or coal system, particularly an old, inefficient one.

If you’re building a new home, it could well be the best option, because it’s comparatively simple to install and you can include underfloor heating at the same time. You could also add solar panels to provide hot water in the summer, which would improve the air heat pump’s ability to heat your home.

Using the controls efficiently will also help to create savings. You’ll probably need to keep the heating on for longer, but at a lower level. Ask your installer how to use the system most effectively.

Could I get any grants or financial help towards installing an air heat pump?

You might qualify for help through the Renewable Heat Incentive scheme or the Renewable Heat Premium Payment scheme.

There are two Renewable Heat Incentive schemes: Domestic and Non-Domestic. They have separate tariffs, joining conditions, rules and application processes. As a homeowner, you would probably need to apply for the Domestic scheme.

Air heat pumps are also eligible for the government’s Green Deal.

To find out more about these schemes, get in touch with the Energy Saving Advice Service on 0300 123 1234 if you live in England or Wales, or Home Energy Scotland on 0808 808 2282 if you’re based in Scotland.

Visit to see how much the call might cost you.

Do air heat pumps need regular cleaning or servicing?

Air heat pumps are very low maintenance, but you should still check them once a year to clear any leaves or debris from the air inlet grill and evaporator. You will also need to weed out any plants that start to grow around the air heat pump unit.

You should get the unit checked by a professional installer every 3-5 years.

As with most heating systems, you should keep an eye on the central heating pressure gauge in your home.

What other types of central heating pump exist?

You can also get ground source heat pumps. They are similar to air heat pumps in that they work like a fridge in reverse – cooling down the earth outside the building and using a heat exchanger to convert this to warmth inside the house.

Like air heat pumps, you need to use them for longer than normal, and they work best with underfloor heating.

In general, they are more popular than air heat pumps, but you need a very large garden to provide enough room for the network of pipes.

How should I insulate my home so it’s suitable for an air heat pump?

  1. Make sure your loft is insulated to an adequate depth
  2. Get cavity wall insulation wherever possible – it could cut around £115 off your heating bill each year
  3. Get draught excluders for outside doors, windows and letterboxes
  4. Replace all your old windows with double glazing – it could save you around £135 each year

How else can I cut my energy costs?

Installing an air heat pump is expensive, so you may want to find other ways to save on your energy bills. To start with, make sure your home and all your electrical appliances are working as efficiently as possible. Here are some suggestions:

  1. When you boil a kettle, only use as much water as you need
  2. Turn appliances off at the wall – don’t leave them on standby
  3. Use energy-saving light bulbs
  4. Defrost your freezer regularly
  5. Slip an insulating jacket on your hot water tank – you could save around £35 a year
  6. When using your washing machine, never set it higher than 30˚

See our full energy saving guide for more details.

It also makes sense to consider switching providers. No matter which energy company you’re currently with, it’s always worth checking the market regularly to see if you could save money by switching.

At OVO, we know that price matters – that’s why we keep our costs down, to help you save. You'll also get our 3% OVO Interest Reward answers on any credit in your account.

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