Air-to-air heat pumps

You’ll need an area outside your home for a unit to be fitted to a wall or placed on the ground near the house. It will need plenty of space around it to get a good flow of air.    

Most homes in the UK use radiators or underfloor heating to distribute heat to each room. These are commonly referred to as ‘wet’ heating systems.  One advantage of air-to-air heat pumps is that they do not require a wet central heating system to warm the home. 

An air-to-air heat pump uses either fan coil units (‘blowers’) or air ducting pipes to deliver warm air. Blowers are usually mounted high on the wall, which can be helpful where wall space is limited. Ducting systems are more likely to be used in new build properties as the ducts are typically mounted inside the ceiling voids to make them less intrusive.  

Air-to-air heat pumps can be single-head or multi-head – where ‘head’ refers to the number of blowers in use. Single-head air-to-air heat pumps have a single outside unit and a single blower inside. Multi-head air-to-air heat pumps have a single heat capture unit outside and multiple blowers inside.

Generally, single-head air-to-air heat pumps installed in the UK are only used in the smallest homes, or for single room heating. If you have more than two rooms, it is likely you will need a multi-head air-to-air heat pump or a ducted system.

As there is no need for a wet central heating system, air-to-air systems using blowers can be very quick and cheap to install. Multi-head installations need to have pipes travelling from the outside heat capture unit to each blower – just as boilers need pipes running to a radiator in each room. Typically, these pipes would run in a slim plastic channel around the upper edges of the room to keep them as unobtrusive as possible. 

Air-to-air heat pumps don’t heat hot water so you will need another way of heating water for showering, bathing and the hot taps. There are several options, and what’s best for you will depend on the amount of hot water your household needs, as well as any space or budget considerations.

You could consider a hot water cylinder fitted with an electric immersion heater, or you might consider using electric showers and ‘point of use’ water heaters. Point of use heaters could use either gas, LPG or electricity to heat the water. Gas-fired heaters will need a flue, whereas electrically heated units can simply be mounted underneath the sink out of sight.

Running costs will depend on how your heat pump is designed and how it’s operated. Savings on your energy bill will also be affected by the system you are replacing.

There is currently very little independent data on how air-to-air systems perform in the UK, so it’s difficult to predict how much money you would save by fitting one. However, we can give some general guidance on what to expect.

Please head to our in-depth heat pumps guide for more information.

Saving money on fuel bills isn’t everyone’s primary motivation for installing a new heating system, but you need to be sure you can afford to run the system once installed. You should ask your installer for an indication of running costs based on their design of the system for your home.

The pipes running to the blowers are all connected to the outside unit. For this reason, blowers are often installed on the inside of an exterior wall near the outside unit, to reduce the length of pipes required internally. Where multi-head systems are planned, the installer would normally aim to minimise the lengths of pipes being run to each blower location, so ask anyone surveying your house about the possible pipe routes so you understand before they start work.