Air Source Heat Pump

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.

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. Heat pumps have some impact on the environment as they need electricity to run, but the heat they extract from the ground, air, or water is constantly being renewed naturally.


The benefits of air source heat pumps
- Lower fuel bills, especially if you are replacing conventional electric heating
- Potential income through the UK government’s Renewable Heat Incentive (RHI)
- Lower home carbon emissions, depending on which fuel you are replacing
- No fuel deliveries needed
- Can heat your home as well as your water
- Minimal maintenance required
- Can be easier to install than a ground source heat pump.

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.

How do air source heat pumps work?

Heat from the air is absorbed at low temperature into a fluid. This fluid then passes through a compressor where its temperature is increased, and transfers its higher temperature heat to the heating and hot water circuits of the house.


Costs and savings


Costs
Running costs will vary depending on a number of factors including the size of your home, how well insulated it is and what room temperatures you are aiming to achieve.

Savings
How much you can save will depend on what system you use now, as well as what you are replacing it with. 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.
- 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 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.

Financial support

You may be eligible to receive payments for the heat you generate using a heat pump through the UK Government’s Renewable Heat Incentive (RHI). 

Domestic RHI is no longer available in Northern Ireland - details of the previous scheme can be viewed at NI Direct.

Updates to RHI regulations affecting heat pumps:

On 6 July 2015 DECC announced further amendments to RHI regulations affecting heat pump eligibility.

The main changes affecting applicants relate to the implementation of the EU directives ‘The Ecodesign of Energy-related Products Directive’ (ErP) and ‘The Energy Labelling Directive’.

Key points of the directives coming into force for heat pumps on 26 September 2015:

- A minimum performance standard for heat pumps that will be raised over time will be introduced.
- A requirement that heat pumps will be sold with EU energy labels, which provide an efficiency rating will be introduced.
- In order to be eligible for the RHI from 26 September 2015 all new heat pumps entering the market must meet these requirements of these directives. And after 25 March 2016 all heat pumps must meet the requirements.


Maintenance

Heat pump systems typically come with a warranty of two to three years. Workmanship warranties for heat pumps can last for up to 10 years, for example through QANW (Quality Assured National Warranties). Many manufacturers also offer options for warranty extensions for a fee. You can expect them to operate for 20 years or more, however they do require regular scheduled maintenance. A yearly check by you and a more detailed check by a professional installer every three to five years should be sufficient.

The installer should leave written details of any maintenance checks you should undertake to ensure everything is working properly. Consult with your supplier for exact maintenance requirements before you commit to installing a heat pump. You are likely to be advised to carry out a yearly 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.

You may also be advised by your installer to check the central heating pressure gauge in your house from time to time. If so, you should be shown how to do this. To prevent the heat pump from freezing in cold winter weather anti-freeze is used. Levels of anti-freeze and its concentration is one of the things that a professional installer will check when he comes to service your heat pump. 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

Before starting, the developer must apply to the relevant planning authority for a determination as to whether the prior approval of the authority will be required for the siting and external appearance of the air source heat pump.