Top menu

Air source

Air Source heat pump overview

Air source heat pump technology has developed rapidly in recent years. Now with inverter driven motors and advanced controls the performance is becoming similar to that of some of the ground source heat pumps, with the advantage of having a price tag very similar to that of an oil boiler, tank and cylinder. This has made them a real alternative to a conventional boiler even without the RHI incentive. With the RHI you have a very attractive financial package with the added benefit of reducing property fuel bills and CO2 emissions.

Contact Greenfields on 01768 210241, for the complete ‘turnkey’ solution, our in house design team can tailor the system design to suit your requirements to enable a complete and bespoke installation.

How it works

An air source heat pump provides energy, extracting low grade heat from the outside air.

The air is drawn across an evaporator, the heat exchanger by a fan. The low grade heat is then compressed to produce high grade heat typically between 35 – 60ºC (up to 70 ºC on some of the higher temperature heat pumps) which is then used to heat your property and provide hot water.

This might sound impossible during the winter months, but the refrigerant in a heat pump boils at between -15ºC and -30ºC there is always energy to be extracted from the air regardless of the weather!

It should be stressed that not every air source heat pump is optimised for the UK climate. As residential and commercial heat pump installers Greenfields recognises that some of the earlier and more budget imported heat pumps are not designed for UK’s climate, and as such will not deliver the required heat and will be constantly icing over. The air source heat pump uses electricity to defrost the evaporator heat exchanger (a defrost cycle). Therefore the more time an air-source unit spends in defrost mode the less efficient it is overall which does result in higher running costs.

Greenfields use several manufacturers to ensure that we can offer the most tailored solution.

Greenfields have a wealth of experience, designing and installing bespoke air source heat pump systems including docking to existing fossil fuel systems or combining with other renewables technologies such as Solar Thermal, Solar PV and Ground Source Heat Pumps.


There are several key considerations when looking to install an air source heat pump:

There are strict MCS guidelines on installation and noise pollution on an air source heat pump.
The unit will require a good flow of air on both the input and exhaust sides. Minimum clearances are generally 350mm free on all sides. The unit will need to be situated on a solid base, or a wall bracket, both will need a suitable condensate drain or soakaway.

Power Supply
Single phase units come in various outputs peaking at 14 kW, larger than that then a three phase electricity supply or 2 single phase units will be required. The local DNO will be able to advise on connection possibilities and requirements.

Connecting to an existing heating system
If you have an existing under-floor heating systems you may not need to upgrade your system, a traditional radiator will need to be upgraded as the heat emitters will need to have a larger surface area as the air source heat pump operates at a reduced temperature when compared to a fossil fuel system. The lower the operating temperature the more efficient the heat pump becomes.

Air Source heat pump running costs

One of the main advantages of an air source heat pump is that you do not have the cost and disruption of laying the ground collectors as you use the air temperature.

It has often been said that an air source heat pump is not as efficient as a ground source heat pump. However, in the spring and autumn months when air temperatures are higher than ground temperatures the air source heat pump can outperform a ground source heat pump, but in the winter months the heating season,
the ground source heat pump will always out perform an air source.

In the winter month’s you could expect an average £3 of energy to cost £1. But in summer you could get up to £5 for your £1.

For more information please contact residential and commercial heat pump installers Greenfields on 01768 210 241.

Greenfields Heat and Power