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

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.

View case studies and examples of homeowners who have installed an air source heat pump.

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. There are two main types of air source heat pump systems.

1. Air-to-water
An air-to-water system distributes heat via your wet central heating system. Heat pumps work much more efficiently at a lower temperature than a standard boiler system would. This makes them more suitable for underfloor heating systems or larger radiators, which give out heat at lower temperatures over longer periods of time.
2. Air-to-air
An air-to-air system produces warm air which is circulated by fans to heat your home. They are unlikely to provide you with hot water as well.

Is an air source heat pump suitable for me?

To tell if an air source heat pump is right for you, there are a few key questions to consider:

• 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.

Costs, savings and financial support

Costs

Installing a typical system costs around £11,000- £15,000. Running costs will depend on a number of factors including the size of your home and how well insulated it is.

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. 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 they are 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 maintain your heat pump efficiency.
• 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.