Out of Office Hours final

Air-Source Heat Pump

Renewable Heat Incentive. Purewater and HeatHeat your home with energy absorbed from the air around you.

Air source heat pumps absorb heat from the outside air. This heat can then be used to heat radiators, underfloor heating systems, or warm air convectors and hot water in your home.

How does it work?

An air source heat pump extracts heat from the outside air in the same way that a fridge extracts heat from its inside. It can get heat from the air even when the temperature is as low as -15° C. The heat they extract from the ground, air, or water is constantly being renewed naturally, saving you on fuel costs and reducing harmful CO2 emission




Unlike gas and oil boilers, heat pumps deliver heat at lower temperatures over much longer periods. During the winter they may need to be on constantly to heat your home efficiently. You will also notice that radiators won’t feel as hot to the touch as they might do when you are using a gas or oil boiler.



The benefits of air source heat pumps
  • lower your fuel bills, especially if you are replacing conventional electric heating
  • provide you with an income through the government’s Renewable Heat Incentive (RHI)
  • lower your home’s carbon emissions, depending on which fuel you are replacing
  • heat your home and provide hot water
  • need little maintenance – they’re called ‘fit and forget’ technology


How much can I save using air source heat pumps?

Your savings will be affected by:

Your heat distribution system

If you have the opportunity, underfloor heating can be more efficient than radiators because the water doesn’t need to be so hot. If underfloor heating isn’t possible, use the largest radiators you can. Your installer should be able to advise on this.

Your fuel costs

You will still have to pay fuel bills with a heat pump because it is powered by electricity, but you will save on the fuel you are replacing. If the fuel you are replacing is expensive you are more likely to make a saving.

Your old heating system

If your old heating system was inefficient, you are more likely to see lower running costs with a new heat pump.

Water heating

If the heat pump is providing hot water then this could limit the overall efficiency. You might want to consider solar water heating to provide hot water in the summer and help keep your heat pump efficiency up.

Using the controls

Learn how to control the system so you can get the most out of it. You will probably need to set the heating to come on for longer hours, but you might be able to set the thermostat lower and still feel comfortable. Your installer should explain to you how to control the system so you can use it most effectively.


Earnings RHIYou may be able to receive payments for the heat you generate using a heat pump through the government’s Renewable Heat Incentive (RHI).For systems installed after 1 August 2011, you may be able to get help with the installation costs of a new air source heat pump through the Renewable Heat Premium Payment scheme.

Is it suitable for me?

Do you have somewhere to put it? You’ll need a place outside your home where a unit can be fitted to a wall or placed on the ground. It will need plenty of space around it to get a good flow of air. A sunny wall is ideal.

Is your home well insulated? Since air source heat pumps work best when producing heat at a lower temperature than traditional boilers, it’s essential that your home is insulated and draught-proofed well for the heating system to be effective.

What fuel will you be replacing? The system will pay for itself much more quickly if it’s replacing an electricity or coal heating system. Heat pumps may not be the best option for homes using mains gas.

What type of heating system will you use? Air source heat pumps can perform better with underfloor heating systems or warm air heating than with radiator-based systems because of the lower water temperatures required.

Is the system intended for a new development? Combining the installation with other building work can reduce the cost of installing the system.



  • Heat pump systems typically come with a warranty of two to three years.
  • Workmanship warranties for heat pumps can last for up to ten years, for example through QANW (Quality Assured National Warranties).
  • A yearly check by you and a more detailed check by a professional installer every three to five years should be sufficient.
  • One of the yearly checks that you are likely to be advised to carry out is to check that the air inlet grill and evaporator are free of leaves or other debris. Any plants that have started to grow near the heat pump unit will also need to be removed.
  • To prevent the heat pump from freezing in cold winter weather anti-freeze is used.
  • If your heat pump has external refrigeration pipes (very unusual for a domestic system) these will need to be serviced annually by a refrigeration engineer.



Planning permission

Air source heat pump installations In Wales and Northern Ireland require planning permission.


From 1st December 2011, domestic air source heat pump systems will be classed as Permitted Development , in which case you will not need planning permission provided that they comply with certain criteria, including:

  • there is no wind turbine at the property
  • the external unit is less than 0.6 m3 in size
  • the unit is more than one metre from the edge of the householder’s property
  • it is not on a pitched roof, or near the edge of a flat roof
  • it meets additional criteria if in a conservation area, World Heritage Site or similar.