What are air source heat pumps (ASHPs)?

Air source heat pumps are a means of heating your home without using fossil fuels. 

Energy is taken from the air and raised to a higher temperature, using a process similar in principle to refrigeration, but in reverse.  That is, the air which is expelled is warm, not cold.  Air source heat pumps can extract heat from air temperatures as low as minus 15 °C.  There are two types of ASHPs:

1. Air-to-air systems provide warm air, which heats a building when circulated via fans.
2. Air-to-water systems heat water to provide heating to a building through radiators or an underfloor system.

 How do air source heat pumps work?

Air is extracted from outside, through the pump and used to heat a home and the hot water.  This is the reverse of refrigeration, where air is drawn out from inside to keep a fridge cool.

There are three parts to an air-source heat pump:

The heat pumps produce hot water to a lower temperature than the usual boiler systems, making underfloor heating the most effective option.

Why should I use air source heat pumps?

ASHP are used when it is not possible to drill in a ground probe or install a surface ground loop on the property – for example if the house is in a rocky area, or has minimal garden.  The only space needed is an outside wall, so they are an ideal solution for apartments and small properties. 

Benefits

Air source heat pump installation costs are reduced, because there is minimal ground work to be done.  There is no need to store fuel, which brings twin advantages of not having to pay up front for a tank of fuel and not having to store it on the property.  As the system runs on electricity, this is ideal for properties without a gas supply, or with restrictions on the use of solid fuels.  For these reasons, it is an ideal solution for urban homes.

If a property is well insulated, the ASHP can provide sufficient heating.  ASHPs operate at maximum efficiency when they are maintaining the temperature at a lower range, such as for underfloor heating.  An outside air source heat pump, when working efficiently, can lower energy consumption for heating by up to 50% when compared to conventional heating systems.

By insulating the property thoroughly, the greatest efficiency can be achieved from the warmth generated. 

The larger the diameter of the pipes used, the less power will be needed to pump the water around, and similarly, the less bends or joints in the pipes route.  This means a well planned location can have a positive influence on the efficiency of the system.

What are the drawbacks for using air source heat pumps?

By using electricity, ASHPs are reliant on a consistent power supply to operate.  This means they cannot provide heat without the presence of electricity, and would be unable to work during a power cut.

The ASHPs when working, do create a noise, estimated at 49 decibels.  This should be considered when selecting a site for the unit: proximity to windows (double glazing) and consideration to neighbours.  However, if the weather is pleasant enough to enjoy being in a garden, the need for heating and hot water is unlikely to be high.

ASHPs should be as close to an external wall as possible – preferably beside it.  This is because there is an increased cost if it is to be sited further away and can influence the effectiveness of the pump.  This may be through the extra distance the air and water must travel – i.e. putting extra strain on the pump. It will also influence the heat losses, if sited further away.  Therefore minimising the heat loss between the pump and the house is vital.

If you are interested in installing air source heat pumps, please complete the online enquiry form.  We will be happy to provide further information or a non-obligatory quote.

Although ongoing expansion plans are in place, the renewable energies team currently operates within a local area comprising Cheshire, Manchester, Birkenhead, Shropshire and North Wales.  Whilst we welcome enquiries from other parts of the country, because we are happy to assist in the provision of information for renewable energy, we are unable to offer a service of delivery on a nationwide basis at this stage.