• Air Source Heat Pumps Guide


    Using similar technology to that in your refrigerator, an air source heat pump is able to absorb ambient heat from the outside air and deliver it into your home for use with heating systems and in domestic hot water. Here we look at how they work, how to tell if your home is suitable and some of the considerations you’ll need to take into account.

    How do air source heat pumps work?

    An air source heat pump works very much like a fridge in reverse. Heat from the outside air is absorbed by a fluid in the pump, and then is passed through a compressor to increase the temperature. This hot fluid then passes through a heat exchanger to deliver heat to hot water and central heating systems for the property.

    How Air Source Heat Pumps Work

    The heat can be used in two main ways:

    1. Air to water: In this system the heat is delivered to a wet central heating system, usually a boiler and radiator set up. The heat that is delivered is at a lower temperature than that produced by a conventional boiler, so over-sized radiators or underfloor heating systems work most effectively.

    2. Air to air: These systems use the heat produced by the pump to circulate warm air around the home, via fan systems. These types of set ups are unlikely to be able to supply hot water.

    Air source heat pumps don’t need a hot day to work effectively, in fact they have been shown to work well in temperatures as low as minus 15 degrees C, so even in the depth of winter you can expect to have good heat generation from this technology.

    Is your home suitable for an air source heat pump?

    Air source heat pumps are not suitable for every home. Here are the things you will need to ask yourself to decide if this technology is right for you.

    Where will it go? An air source heat pump will need to be situated outside your home. It can either be fitted to the wall or simply placed on the ground outside the building, but will need to be in a secure location to avoid tampering and somewhere where it can get a good flow of air.

    How good is your insulation: Air source heat pumps produce heat at a lower temperature than a traditional boiler system, so for this reason a well-insulated property is essential. Make sure you have your loft and walls insulated up to modern standards, and that you have draught proofed your home where necessary.

    How do you heat your home currently? Air source heat pumps offer the most savings, both financial and in terms of carbon, when they replace electric, coal or oil fired heating systems.

    How will the heat be delivered to your home? If you plan to use radiators, chances are you will need to upscale your current radiators to accommodate the lower temperature of the heat, which is a cost you will need to factor in. Alternatively you may wish to use underfloor heating, which will also be at a cost if you don’t have this in place already.

    Other considerations about air source heat pumps

    There are a number of things you should know about air source heat pumps before deciding to install them. On the positive side, air source heat pumps are far cheaper than ground source to install, with typical costs ranging from £10,000 – £14,000, and don’t come with the same problems of lots of digging and disruption outside your home. However, the savings are significantly less too, although there is still a good potential for savings if you currently heat your home with electricity or coal.

    Air source heat pumps can also be a great commodity for hot summer days, as the units can be run in reverse to provide cold air as an air conditioner. Air to water heat pumps are eligible for the Renewable Heat Incentive, although at a lower rate than ground source heat pumps.


    Air source heat pumps are a great way for householders who are off the gas grid to access lower cost, greener heat for their homes. It is important to consider where the heat pump itself will go, as well as any modifications needed to your current heating system internally to accommodate the lower temperatures they produce. As a lower cost technology they are more accessible for many householders than ground source heat pumps, but adopters should be realistic about the financial and carbon savings achievable with this technology.