An air source heat pump extracts energy from the air outside the house in the same way that heat is extracted from the inside of a fridge.
Heat from the air is absorbed by a fluid which is pumped through a heat exchanger. This fluid passes through a compressor, and is concentrated into a higher temperature, capable of heating water for the heating and hot water circuits of the house. The process then repeats.
The pump can extract heat from the air even when the outside temperature is below freezing.
Unlike gas or oil boilers, heat pumps deliver heat at lower temperatures over much longer periods. This means that radiators should never feel as hot to the touch as they would do when using a gas or oil boiler.
To see if an air source heat pump is right for you, you should consider a few things:
You’ll need a place outside your house to put the unit: a wall, or space on the ground. It will need plenty of space around it to get a good flow of air. Planning permission will be required for this, and you should check with your local council.
Since air source heat pumps produce heat at lower temperatures than traditional boilers, it’s important that your home is well insulated and draught proofed. It could also make the system cheaper and smaller.
If you’re replacing an electric, LPG or coal powered system, an air source heating system will save you more on your heating bills. Heat pumps are not recommended for homes on the gas network.
Underfloor heating systems, larger radiators or low temperature fan convectors (warm air heating) can perform better than standard radiator-based systems because of the lower water temperatures required.
The costs of installing the system can be lowered if you’re combining the installation with other building work.
Installing a typical system will start from around £7,000. There are grants and loans available to help with these costs. Running costs will depend on a number of factors, including the size of your home and how well insulated it is.
Some of these factors are outlined below. It’s also important that the controls for the system are set according to your needs.
Underfloor heating provides greater efficiencies than radiators, because the water doesn’t need to be heated to such a high temperature. If underfloor heating isn’t an option, then use the largest radiators you can.
You will still have to pay some fuel bills, because the heat pump itself is powered by electricity. The saving you achieve will be affected by both the price of the fuel you are replacing, and the price of the electricity for the heat pump.
The efficiency of the old heating system will have affected the cost of your energy bills. If the old heating system was inefficient, your bills could have been high, and so the difference between the new running costs and the old running costs will be bigger.
It’s a good idea to set thermostats to somewhere between 18-21C. If you dramatically increase the temperature of your house after installing a new heat pump system, your heating bills will very likely increase!
We advise that you take some time and learn how to control the system, so you can get the most out of it. We will explain this before we leave, as well as providing a handover pack including manuals. We can also give you advice about how to control the system to make it most effective.
You can read about one of our air source heat pump installations in our case studies.