Your home may be fitted with an Air Source Heat Pump (sometimes called an air-to-water heat pump) to heat your home.

It works by transferring heat from the outside air to the water in your central heating system. The Air Source Heat Pump (ASHP) captures outside air which is blown over a network of tubes filled with a refrigerant. This warms up, and it turns from a liquid into a gas. It’s passed through a compressor, into a heat exchanger and surrounded by cool water, making it warm. This warm water is then circulated around your home through underfloor heating and radiators to provide heating and hot water. This is shown in the diagram below:

 

Heat pump diagram showing the four stages of the refrigeration cycle from the Energy Saving Trust. Heat pumps: how they work, costs and savings - Energy Saving Trust

The heat pump is designed to work in heating with a low to medium flow temperature. The temperature of the water flowing through your heating system will be between 35-45°C, rather than 60-80°C, which would be the case for a traditional gas boiler system.

Radiators will feel cooler to touch compared to a traditional system, but they will be sized to ensure each room stays warm and comfortable, even on the coldest days. An ASHP will operate continuously to maintain the room temperatures set on the thermostat, rather than a gas boiler system which tends to react more quickly – providing intense heating to reach required temperatures, which may take shorter periods.

To get the best from your new heat pump heating system, the controls and settings are very important and we’d recommend the manufacturer’s settings are left unaltered; amending these could impact on the system’s efficiency and lifespan. Please refer to the manufacturer’s guidance for more information.

Benefits

There are two main benefits of ASHPs over traditional boiler central heating:

• Reduce your energy use: unlike traditional boilers (which use fossil fuels), heat pumps use electricity. And heat pumps are more than three times more efficient than a gas or oil boiler, helping to lower your energy use.

• Improve your carbon footprint: your CO2 emissions will be lower with a heat pump compared to other types of heating. This is because they don’t use fossil fuels, instead taking heat from their environment. There is a common conception that ASHPs are cheaper to run but this largely depends on what heating system you have in your previous home along with the cost of your electricity tariff as well as how you control your heat pump.

Generally, heat pumps should be cheaper to run than most other fuel types because they’re so much more efficient. However, if you have a newer gas or oil boiler, heat pumps are likely to be slightly more expensive to run. This is because electricity is usually more expensive per unit compared to gas or oil.

More information and latest cost comparisons can be found online at: Heat pumps: how they work, costs and savings - Energy Saving Trust