Air Source Heat Pumps

Generate your own heat at home and enjoy the lowest running costs and lowest carbon emissions of any heating system with an Air Source Heat Pump.

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How it works

Sometimes understood as a ‘fridge in reverse’, an Air Source Heat Pump uses free heat from outdoor air as low as -20°C to generate energy to heat your property.

  • The Air Source Heat Pump uses a fan to draw air into it and over a heat exchanger, which contains a refrigerant liquid
  • An evaporator uses the latent heat from the air to heat the refrigerant liquid sufficiently until it boils and turns into a gas
  • This gas is then compressed which causes it to significantly increase in temperature
  • An additional heat exchanger removes the heat from the refrigerant (turning it back into liquid) and uses it to heat the water for your heating system

A must for new builds

Developing a sustainable, well-insulated property with low running costs is one of the great joys of a major new project. 

Air Source Heat Pumps can be 300% efficient when they are able to gently heat the fabric of a building and continually provide warmth at the same rate it is lost. During a new build, it is much easier and cheaper to install the necessary pipework, and heat pumps can integrate well with underfloor heating.

Perfect for pools

Air Source Heat Pumps are an economical way of heating your swimming pool as heat from outdoor air can be captured and used to heat the water. If you wanted to use your pool in the middle of winter, you could still rely on an Air Source Heat Pump to keep it warm as it operates in temperatures as low as -20°C. Using automation, you can set your favourite pool temperature and let the heat pump do the work.

Heat pump size will depend on the size of your pool and other elements such as the thermal properties of your pool structure, wind speed, water velocity and water table. Once installed, you’ll enjoy low running costs and no carbon emissions as you spend time in your pool.

Planning permission

Depending on its size, visual impact and level of background noise, an Air Source Heat Pump may need planning permission under the provisions of the Landing Planning and Development (Guernsey) Law 2005.

More information



In a well-insulated property, Air Source Heat Pumps can be around 300% efficient. 

This means that for every kW of electricity used to power the system, the heat pump will produce 3kW of heat for your property. The heat pump’s low running costs are thanks to clever mechanics that convert heat from outdoor air into heat for your home.

Office heating

Air Source Heat Pumps are being used more and more in commercial and other non-domestic properties such as offices, shops, and schools. 

Office Air Source Heat Pumps can:

  • Significantly reduce heating bills 
  • Cool an office to provide a controlled climate

A well-designed, correctly installed system should require minimal maintenance and last around 20 years or more.

How much does an Air Source Heat Pump cost to install?

An Air Source Heat Pump is a lifetime investment for your property. It could help increase your property value and will significantly reduce your bills. 

You should always ask for two or three quotes before making a final decision. However, the average cost is around £9,000 – £12,000. As an Air Source Heat Pump can last around 20 years, the low running cost means it’s possible to pay back the initial investment relatively quickly. 

It’s worth noting that Air Source Heat Pumps are a better solution for well-insulated properties and new builds. Heat pumps generally aren’t designed to take a property from a cold to warm state as quickly as possible. You may need larger radiators if you are installing a heat pump retrospectively. 

Older, draughtier properties need higher operating temperatures to maintain an enjoyable internal climate. Although heat pumps can work at higher temperatures, this will reduce their 300% efficiency which will impact your cost and environmental savings.

How much does an Air Source Heat Pump cost to run?

Compared to all other heating sources, Air Source Heat Pumps are by far the cheapest to run. 

Boiler type:

Gas: £1,342

Oil: £389

Electric: £776

Air Source Heat Pump: £353 


Heating running cost calculation based on 8100 units a year, as of October 2020. 

Tariffs on each heating source may change over time. As a rough comparison, Air Source Heat Pump running costs are 9% lower than oil and 74% lower than gas.

How is an Air Source Heat Pump more environmentally friendly?

Air Source Heat Pumps produce the lowest carbon emissions of any heating type.

This is because they operate at an efficiency rate of up to 300%, therefore, for every kWh of electricity consumed they deliver around 3kWh of heat to your home or commercial premises. Due to this efficiency an Air Source Heat Pump installed in your property will reduce the greenhouse gas emission from your heating system by at least 88% when compared to an oil or gas heating system.

How is it possible to have 300% efficiency?

Air Source Heat Pumps generate their own heat using outdoor air, and use low-carbon electricity to drive the system. 

Depending on the level of insulation in your property, Air Source Heat Pumps can provide you with £3 worth of heat for every £1 you’ll spend on the electricity required to run your heat pump. 

The full definition is a ‘Coefficient of Performance (COP) of 3’. Energy cannot be created, it can only be converted into another form – such as heat energy – meaning it’s impossible to have more energy produced (heat) than is put in (electricity).

If 1kW of electrical energy is used to drive the compressor and pumps, the remainder is transferred from outdoor air – a heat source that would otherwise not be used. The refrigerant inside the heat pump boils at a very low temperature, which explains why Air Source Heat Pumps work in temperatures as low as -20 degrees C.

The free heat from the outdoor air is not considered an energy input, but is used to produce 3kW worth of valuable heat energy for your home within the mechanics of a heat pump.

Thinking about switching to electric heating?

It pays to plan ahead. Electrical installations are an investment and can take time to complete. Contact your preferred installer as early as possible to find out what you need to do.

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