What are air source heat pumps and how do they work?

Heat pumps can help reduce emissions.

Air source heat pumps are a clever alternative to traditional boilers. They create a lot less CO2 so they’re much better for the planet and your surrounding air quality. And now you can apply for regular cash payments from the government to help towards your overall costs. So let’s demystify air source heat pumps to help you decide if they’re right for you and your home…

What is an air source heat pump?  

By using the same clever technology found in your fridge freezer (only now in reverse), an electric-powered air source heat pump warms your home using your outside air. The science behind it has been around for many years and was even described by Lord Kelvin back in 1852.

How do they work?

Air source heat pumps pull in air from outside and use it to turn liquid into gas. This vapour is then compressed to increase its heat (creating warmth for your home) before the gas expands back into liquid to begin the process again. And air source heat pumps (ASHPs) even work when its cold outside – right down to temperatures as low as -15°C

Pros and cons of air source heat pumps

What's great:

  • Can heat your home more cost efficiently than a hot water boiler system
  • Much better for the environment, cutting down your home’s CO2 emissions and improving local air quality
  • Get quarterly payments through the existing Renewable Heating Incentive – between now and March 2022, that’s up to £9k
  • Some models can be used with solar panels for a more self-sufficient system

Potential challenges:

  • Some properties won’t have the right space, access or surroundings for a heat pump installation
  • To get the best efficiency from ASHPs, it’s best if your home has good insulation to keep the warm air inside longer
  • Most homes will need bigger central heating pipes installed to increase the flow rate around the system
  • Bigger radiators may also be needed to combat heat loss at lower temperatures

Renewable Heating Incentive


To incentivise more homes to choose renewable heating, the government's current scheme can help you switch to an air source heat pump. And if you meet the criteria, you’ll receive quarterly payments (up to £9,000 over seven years) based on how much renewable heat your system produces. Just make sure you apply by March 2022, as a replacement scheme – just announced in the Government’s Heat and Buildings Strategy – will be effective from April 2022.

Interested to find out more? Get in touch here

So is an ASHP right for you?

There are a few things to think about when it comes to considering air source heat pumps. Is your current heating system past its best? Do you have the exterior space alongside your home that can easily fit a heat pump unit? 1 And is your home properly insulated to make the most of the heat pump – or is that something you’d consider? If the answer is yes to these, an air source heat pump could be a more efficient, low-carbon heating choice for your home.

Back to the Source

Additional information

  1. Minimum space needed: Up to H: 1,565mm W: 1,100mm D: 450mm plus clearance around the pump.