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A Guide to Air Source Heat Pump Efficiency

Author: Jack Lloyd
Updated: Oct 24, 2023
10 minutes read
  • A typical efficiency rating for air source heat pumps is around 300%
  • That’s 3x better than gas boilers
  • They can reach that level without polluting the planet
  • VAT has been scrapped from 5% to 0% on air source heat pumps for the next five years

With gas boilers being banned from 2035, the future's looking good for air source heat pumps and their already miles ahead in terms of efficiency. Plus they’re renewable as they’re purely powered by electricity.

Not only is this great but their cost is also coming down, especially as the government’s Boiler Upgrade Scheme is providing homeowners with a £7,500 discount if they replace their gas boiler with a heat pump.

With the energy price cap being so volatile, gas bills fluctuate a lot, which means the running costs of air source heat pumps are cheaper than gas boilers, seeing as they are so much more efficient.

And now homeowners can also enjoy paying 0% VAT as the VAT has been scrapped from 5% to 0% on air source heat pumps.

This article will explain about air source heat pump efficiency and how much more efficient an air source heat pump is compared to other heating systems, and what makes them better.

Modern house with an illustration of how air source heat pumps work

How Efficient Are Air Source Heat Pumps?

Typically, the air source heat pump efficiency rating is that of 300%, although the best ones can actually reach much higher.

Meaning that on average, air source heat pumps produce three units of energy for every unit of electricity they absorb.

For context, the average UK home uses just over 12,000 kWh per year for heating, and a heat pump would be able to provide the same amount at just 4,000 kWh.

When compared, electric boilers are in fact four times worse, with an efficiency rating of 100% and at most, the best gas boilers can only reach 98% efficiency.

Usually, electricity is around four times more expensive than gas, which may seem to cancel out any gains you would make from using air source heat pumps. However this is not true when it comes to operation.

Clean electricity is fast becoming the best way for the UK to reach its goal of net zero emissions by 2050.

You would be making a solid investment in a future that’s almost here and one which will save you a huge amount on your heating bill when it finally does arrive.

Why Are Air Source Heat Pumps So Efficient?

The reason the efficiency of air source heat pumps is four times more efficient than gas and electric boilers is because they don’t have to burn fuel or slowly convert electricity into heat.

Instead, they transfer warm air from outside to inside your home, by allowing it to blow through a compressor and heat exchange, where it then automatically turns into hot water.

With air source heat pumps, you can find out how efficient any given model is by looking at its Coefficient of Performance (CoP). For a full picture, it’s better to check the Seasonal Performance Factor (SPF).

The CoP will tell you a machine’s peak efficiency, while the SPF tells you on average, the heat pump’s efficiency over the course of a year.

During The Winter, How Efficient Are Air Source Heat Pumps?

In the winter, air source heat pumps are around 20% less efficient. This is due to needing more electricity to draw the heat from the air.

Even if it was snowing, air source heat pumps are still around 2.5 times more efficient than gas boilers.

If the temperature falls below freezing, you don’t need to worry about your air source heat pump breaking down. Most modern heat pumps will continue to work when it’s as cold as -10°C, and the most efficient models will still keep you warm at -25°C.

This is because there’s still heat in the air at this point. For there to be no heat at all, it would have to be -273°C and fortunately for England, we don’t experience winters that bad.

Although it is advised that during the winter you carry out maintenance checks more regularly, since the weather can get particularly worse during these months.

If the weather is particularly extreme in your area, then perhaps you can consider getting a heat pump cover, which helps shield the unit outside against any debris and snow.

Are Heat Pumps More Efficient Than Gas Boilers?

Yes, heat pumps are far more efficient than gas boilers.

Typically, the efficiency ratings of air source heat pumps are three times better than gas boilers, and sometimes up to five times better.

The reason why heat pumps can champion other fossil fuel counterparts is due to their ability to produce about three units of heat for every unit of electricity they’re given, whereas gas boilers only produce about 0.96 units of heat from one unit of gas.

Air Source Heat Pumps vs Gas Boilers

When it comes to looking at the cost of air source heat pumps and gas boilers, it pays to look at not only the installation cost, but the operational costs involved. Across buying and operating, air source heat pumps work out cheaper.

Please note that these prices are an estimate and that costs will vary depending on the size, make and model. The cost of the heat pump includes the £7,500 discount through the Boiler Upgrade Scheme.


  • Installation Cost: £2,475 (Includes £7,500 grant + no VAT)

  • Yearly Running Cost: £723 - £964

  • Average Lifetime: 20 to 25 years

  • Installation Cost Per Year: £249 (20 yrs) to £199 (25 yrs)

  • Total Cost (10+ years): £12,128 (£2,488 installation + £9,640 running)


  • Installation Cost: £2,700

  • Yearly Running Cost: £984

  • Average Lifetime: 10 to 15 years

  • Installation Cost Per Year: £180 (15 yrs) to £270 (10 yrs)

  • Total Cost (10+ years): £12,540 (£2,700 installation + £9,840 running)

Result: Over 10 years, heat pumps average at £412 cheaper.

Government Grants Available For Air Source Heat Pumps

There is currently only one government grant available for heat pumps. This scheme provides financial support to cover some of the cost of air source heat pump installation.

The Boiler Upgrade Scheme

Originally called the Clean Heat Grant, the Boiler Upgrade Scheme is there to help people replace their boilers with a more eco-friendly alternative, such as air source heat pumps.

Running from April 2022 until April 2025, the Boiler Upgrade Scheme replaced the Domestic Renewable Heat Incentive (RHI), which closed to new applicants on 31st March 2022.

How Does It Work?

With this scheme, homeowners in England and Wales will be able to get up to £7,500 off the cost of a new air or ground source heat pump.

The grant operates on a first-come, first-served basis, so customers need to register their interest fast. The installer automatically deducts the grant from the installation cost, giving you cheaper air source heat pumps without fuss.

This will reduce the general cost of an air source heat pump from £9,500 to £2,000 which works out cheaper than a new gas boiler. However, due to the scheme receiving £450m, a maximum of just 90,000 homes will be able to take advantage of the grant over the next three years.

What Is The Most Efficient Air Source Heat Pump?

Currently, the most efficient air source heat pump is the Hitachi Yutaki M RASM-4VNE. It has an efficiency of 500%, which means it produces an impressive five units of heat for every unit of electricity.

Hitachi’s model produces 11 kW of heat, which is more than capable of heating the average house, and will even offer enough heat for a 200m² home.

Plus if your supplier uses the government’s Boiler Upgrade Scheme, you can buy it with a discount of £7,500.


If an air source heat pump sounds appealing to you then the next step would be to do some research to see which model would be better suited to your home.

When you do get your new heat pump installed, make sure your chosen company uses the Boiler Upgrade Scheme to get you a discount of at least £7,500.