How air source heat pumps work
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. The heat they extract from the ground, air, or water is constantly being renewed naturally, saving you on fuel costs and reducing harmful CO2 emissions.
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.
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.
Air source heat pumps are more suitable for underfloor heating systems or larger radiators, which give out heat at lower temperatures over longer periods of time.
The benefits of Air Source Heat Pumps
What Air Source Heat Pumps (also known as ASHPs) can do for you and your home:
- Lower your fuel bills, especially if you are replacing conventional electric heating
- Get paid for the renewable heat you produce through the government's Renewable Heat Incentive (RHI).
- You earn a fixed income for every kilowatt hour of heat you produce. This is likely to be used in your own property, but if you are lucky enough to be connected to a heat network you might be able to get an additional payment for 'exporting' surplus heat.
- Lower your home's carbon emissions, depending on which fuel you are replacing
- Heat your home and provide hot water
- Virtually no maintenance, they've been called 'fit and forget' technology
- Easier to install than a ground source heat pump.
Get paid for the renewable heat you produce!
The Renewable Heat Incentive is a government incentive scheme designed to reward those who use renewable energy to heat their buildings. It will be available to households in spring 2014.
After joining the RHI scheme, homes will receive a quarterly tariff payment for every kilowatt hour (kWh) of renewable heat they produce.
The RHI supports the following technologies:
- Air-to-water heat pumps
- Underfloor heating
- Biomass-only boilers and biomass pellet stoves with back boilers
- Ground and water source heat pumps
- Solar thermal & PV panels
What you can save with Air Source Heat Pumps
Your savings will be affected by:
- Your heat distribution system Underfloor heating is far 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.
Is it right for you?
Here 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.