Air Source Heat Pumps work in a very similar way to ground source heat pumps, except instead of taking heat from the ground; they extract heat from the air. It is possible to extract heat from air even when the outside temperature is as low as minus 15 degrees!
An air source heat pump is usually placed outside a property to the back or side, the system looks similar to the old style air conditioning units. The air source heat pump takes heat from the air and using electricity the pump heats this to a higher temperature and then distributes it to either radiators, under floor heating, warm air convectors or to heat hot water for use in the home.
Like ground source heat pumps, the air source pump does rely on electricity, but this is less than the heat it produces, making it a good alternative source of energy. Air source heat pumps are a lot easier to install than ground source pumps as they tend to be attached to the outside of the property. The system comprises of a heat exchanger, an evaporator, a compressor and a condenser. It is possible to use an air source heat pump in the summer to produce cooler air. The two types of system available are, air to water systems and air-to-air systems.
Air to water systems take heat from the air and use it to heat water in the central heating system. Depending on the system installed, it is sometimes advised to install larger radiators or to move to under floor heating to get the most out of the system, as the heat produced is a lower temperature to traditional systems.
Air to air systems take heat from the air and use fans to feed it into the home. This type of system is not able to produce hot water.
Air source heat pump costs
Air source heat pumps are cheaper than ground source heat pumps; this is mainly due to the installation being much simpler. The Energy Savings Trust estimates the cost to be between £6,000 and £10,000 for an installation to a detached property. It is estimated that air source heat pumps can save a typical property up to £330 a year; this is based on replacing an electric system.
Savings possible from air source heat pumps
As with ground source heat pumps the savings can vary greatly as they are highly dependent on a number of factors, some of which are detailed below.
The chosen heat distribution system – as the different systems such as under floor heating and radiators perform differently, this has an impact on the savings that can be seen. Under floor heating is the preferred heat distribution method for air source heat pumps.
Fuel costs will affect the possible savings – this needs to be looked at in two ways. Firstly it depends on the cost of fuel that is being replaced and secondly it depends on the cost of fuel to power the heat pump.
Efficiency of the system being replaced – this will vary between installations, even if the system is the same type of fuel, how efficiently it worked would have always been affecting the energy bills. This then has an effect on the savings that can be seen from the air source heat pump. For example if the old system was very inefficient then the savings will be greater than if the old system was very efficient.
The use of the heat produced – if the heat pump is being used to heat water this is less efficient than heating space, therefore the savings are likely to be lower.
The use of the system – the savings that can be seen will be dependent on how the new system is used in comparison to the old system. For example, if the new system is used to take the heating to higher temperatures than the old system, then this is likely to eliminate any savings.
Controlling the system – it is important that the installation team demonstrate how to use an air source heat pump most effectively and efficiently. It is a very different system to traditional heating; therefore knowing how to maximize the benefits of the system can be key to saving money.
Benefits of air source heat pumps
Installing an air source heat pump can result in large savings on energy bills, but this is dependent on the system that is being replaced, for example savings will be greater if an electric system is being replaced.
Air source heat pumps can reduce your carbon footprint and reduce your property's carbon emissions.
Air source heat pumps do not require any type of fuel to be delivered. They are often thought of as 'fit and forget' systems as they require very little maintenance.
Air source heat pumps can be used to supply hot water and space heating.
Air source heat pumps are easier to install than ground source heat pumps, although they tend to be slightly less efficient.
Is an air source heat pump suitable for my property?
Air source heat pumps require space on a wall or at ground level that has plenty of space around it to make sure there is enough air circulating. Air source heat pumps are only advisable if a property is already well insulated, as they produce heat at lower temperatures than traditional heating systems, meaning if the home is not well insulated or is very draughty the system will be ineffective.
It is important to consider which fuel is being replaced by the air source heat pump; the system will pay for itself far quicker if it is replacing an electric system. Heat pumps are generally not recommended for properties that currently use gas. It is also key to look at the system being used to heat the property, as under floor heating is much more effective than traditional radiators due to the lower temperatures produced by an air source heat pump. Air source heat pumps can be retrofitted, but the costs are greatly reduced if the system is being installed into a new property development.