Air source heat pumps explained

Air source heat pumps


Thinking about installing air source heat pumps in your housing stock?

Air source heat pumps (ASHPs) are a highly efficient way to heat a home. The beauty of them is that they can work by themselves or in partnership with existing heating systems to give you affordable heat and hot water all year-round.

What is an air source heat pump?

There are two main types of air source heat pumps: air-to-water and air-to-air. The most familiar is the air to water.

They are a major source of home heating in Scandinavian countries like Sweden, Norway, Denmark where they have been used successfully for over 50 years. It is a unit that replaces or can work alongside your current gas or oil boiler.

If you have storage heaters then it will replace them as part of a full heating system with traditional radiators replacing the storage heaters.

The unit is sited outside your property in a suitable location identified at point of survey. It looks remarkably like the aircon units we are all used to seeing on holidays abroad.

How does an air source heat pump work?

An air source heat pump works very similarly to a fridge in reverse (don’t say that to an engineer).

It transfers heat released by the refrigerant via a plate heat exchanger to the water in the heating system.

As we all know water boils at 100c, refrigerants used in heat pumps boil at temperatures as low as minus 48c. This is how they can still produce heat even when the air passing over them is below zero.

With a typical monobloc unit refrigerant is confined to the unit and does not become any part of the internal heating system in your home.

Are air source heat pumps noisy?

Modern air source heat pumps are really quiet. In fact, they can even be quieter than a gas boiler! For example: a Daikin Altherma 3HT is quieter than a Worcester Greenstar 30i

Sound power level: 54dB outdoor Sound power level: 55dB indoors.

What are the benefits of an air source heat pump?

  • Can provide significant savings on energy bills
  • Is powered by an infinite source of energy
  • Air to Water heat pumps are eligible for the government RHI scheme
  • Will reduce carbon emissions
  • Zero fuel deliveries required
  • No Flue to have to get to outside unlike a boiler
  • No gas required in the property for the heat pump
  • No worrying about gas leaks

Our client Bolton at Home reported energy savings of up to 70% after the installation of an air source heat pump in their property.

Bolton at home

What about servicing an air source heat pump?

Just like your gas boiler they do need servicing; unlike your gas boiler this does not have to be every year unless it is a split system. but you should get an air source heat pump serviced professionally at least every two to three years to ensure it’s working at its absolute best.

One of the best things about ASHPs s is that they require very little user maintenance. The only thing you need to ensure is that there’s plenty of air being supplied to the air source heat pump. Which does mean checking to ensure the fans are clear of leaves/rubbish, if there’s any plants close to the ASHP you should ensure that they’re pruned back and they’re not too close to the pipes or unit.

Thinking about installing an air source heat pump?

If you’re considering installing an air source heat pump we can help. We’ve been installing air source heat pumps across the country for housing association for several years now, and we’ve also helped them with funding and monitoring so that they can get a clearer picture of how their air source heat pumps are performing in real-time.

Get in touch on: 0161 543 4128 or email us at:

About Thermatic Homes

Thermatic Homes a national M&E contractor based in Greater Manchester that provides a one-stop solution for housing associations, from mechanical and electrical services, to build and renewable energy installations and training.

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