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See moreUsing air-to-air heat pumps for air conditioning
Air-to-air heat pumps provide air conditioning in summer as well as heating in winter. See how they work and whether you are eligible for a £2,500 government grant.
Most UK homes are designed to keep the heat in rather than out, and very few have air conditioning. When a heatwave hits, our homes can quickly become uncomfortably warm, stuffy and much too hot for sleeping.
It's an issue that's becoming more frequent. In July 2022, a new all-time temperature record of 40.3°C was set – the first time it has exceeded 40°C in the UK since records began.
Record-breaking heatwaves in May, June and July 2026, have left people struggling to keep their homes cool up and down the country. High overnight temperatures make it even more difficult for properties to cool down as heat accumulates over multiple days of hot weather.
Keeping our homes cool in summer as well as warm in winter is increasingly becoming a priority for UK households.
So how can you keep cool in the heat of the summer? Despite its name, a heat pump could be the answer.
If you're looking for a quick fix and aren't ready for a new heating system, read our guide to electric fans and portable air cons: Should you buy an air conditioner or an electric fan this summer?
Air-to-air heat pumps that double up as air conditioning
The most obvious type of heat pump for cooling your home is an air-to-air heat pump. These are different from the air-to-water (hydronic) heat pumps that are predominantly being installed in UK homes to replace gas and oil boilers.
Air-to-air heat pumps are popular in mainland Europe, where the climate is warmer, and they are used for cooling as well as heating.
In theory, there is little difference between an air conditioning system and an air-to-air heat pump. If the unit is reversible, it can provide both heating or cooling. But not all do this.
In winter, air-to-air heat pumps take heat energy from the outside air and use it to heat air that is then circulated around your home. In summer, the process is reversed – excess heat is drawn from inside your home and expelled outside, while cool air is recirculated back into the room, reducing the indoor temperature. It's similar to the process that happens to lower the temperature inside your fridge.
Individual and mini-split units
Either hot or cold, the air is delivered into each room via units that can be either wall-mounted, floor-standing or concealed within the wall.
One main outdoor air-to-air heat pump unit can be connected to up to five indoor units. In this type of 'mini-split' system, the indoor units are connected to the outdoor unit by pipework carrying the refrigerant around your home. The pipes are relatively narrow and unobtrusive - similar in size to the water pipes you see connecting to your radiators in a traditional central heating system. But you'll need to install them into to each room, usually at a high level on the wall/ceiling, where they can then be concealed or boxed in.
Ducted systems are also available, but this can be disruptive to install unless you already have ducted warm air heating, which is uncommon in the UK.
Individual, wall-mounted 'monobloc' units are also available. They don't need an outdoor unit – just a couple of holes drilled through an external wall – so they are a good solution where external heat pump units are not permitted. However, these units only heat and cool one room, so they're not a whole-house solution.
An air-to-air heating and cooling system can be especially cost-effective if you have a smaller house or flat with relatively few rooms. It is especially worth considering if your home often overheats in warm weather.
If you're already using electric heating rather than a wet system, the switch would be cheaper and more straightforward.
You'll also see lower running costs than with other types of electric heating and plug-in air conditioning.
Looking for a heat pump that will connect to a wet radiator system instead? Find out more about how heat pumps work and air-source heat pumps.
How much do air-to-air heat pumps cost?
Air-to-air heat pumps are cheaper to buy and install than air-to-water heat pumps. According to the Energy Saving Trust, it costs around £1,900 to install a single-unit system to serve a single room, or around £3,700 to add a multi-unit system to a three-bedroom semi-detached house.
You will also need to consider the costs of any additional work needed to remove your existing heating system and provide hot water.
The government has recently expanded its Boiler Upgrade Scheme to give homes in England and Wales a grant of £2,500 towards the cost of installing an air-to-air heat pump while replacing a fossil-fuel system. You can't use the grant to add an air-to-air heat pump as an additional heating/cooling system alongside a gas or oil boiler.
To access the grant, you need to have the work carried out by an MCS-certified heat pump installer, who will be able to apply for the funding on your behalf.
The MCS (Microgeneration Certification Scheme) code of conduct means installers should not use high-pressure selling techniques, misrepresent the benefits of a heat pump in your home, or offer you better rates if you agree to do marketing for them. You can search for certified heat pump installers through Which? Trusted Traders to find a company that we've also vetted and hold to strict standards.
As with any home improvement project, we recommend getting a number of quotes from different installers to compare what is offered.
What else do you need to know about air-to-air heat pumps?
- An air-to-air system is a good alternative to other types of electric heating (storage heaters or electric panels). If you don’t already have a ‘wet’ system (pipework and radiators) installed, an air-to-air heat pump can be installed with minimal disruption. If you do currently have gas-heated radiators, the switch over will be a bit more complicated.
- Air-to-air heat pumps are much more efficient to run than a direct electric heating system (such as electric panel radiators or storage heaters). That means you should see lower running costs in the winter months than with other electric heating options.
- While they are also efficient for air cooling, remember that if you don't currently have air conditioning in the summer then using an air-to-air heat pump for cooling will considerably add to your annual energy usage. Make sure you prioritise passive cooling measures (for example, adding insulation and shading) to reduce your need for air conditioning.
- Air-to-air heat pumps are programmable, just like other heating systems and often come with a remote and/or smart wi-fi option to control the temperature, timing and air flow. Many can also offer dehumidification and air purification functions.
- You only need one external heat pump unit for up to five internal units (i.e. five rooms), so if you need to heat (and cool) a relatively small home, an air-to-air system could fit the bill.
- You'll need to think about your hot water provision. Some air-to-air systems can be connected to a domestic hot water tank to provide your hot water, although not all do this. If your hot water is already provided by separate, electrically powered means, such as an electric immersion heater or point-of-use water heaters, you don’t need to replace this. Otherwise, you'll need to factor in the installation of a new water heating system.
Case study: Hear from a Which? member who installed an air-to-air heat pump in a top-floor London flat.
Can all heat pumps cool your home?
The most popular type of heat pump in the UK is a hydronic air-to-water heat pump. These are preferred as they are a more direct gas boiler replacement. They heat your home by circulating hot water through radiators and/or underfloor heating in your existing central heating pipework.
Some hydronic heat pumps can also provide cooling by reversing the process of transferring heat from one place to another. But not all hydronic heat pumps can do this, so if you are interested in a system that also provides cooling, discuss this with your heat pump installer when you are getting quotes, and check the specifications carefully before choosing a heat pump system.
You’ll also need the right sort of emitters to make the most of cooling via an air-to-water heat pump system:
- Heat pump convectors: Replacing standard radiators, heat pump convectors look similar to electric panel radiators and can be floor-standing or wall-mounted. They have a built-in fan that draws air from the room across a heat exchanger, cooling (or heating) the room as required.
- Underfloor heating: A heat pump can pass chilled water through underfloor piping to cool the floor. This absorbs heat from the air, thus reducing the temperature of the room. However, careful design is needed to prevent the formation of condensation on the floor, and this may not be the ideal choice for you if you dislike having a cold floor in your home.
If you're considering a heat pump for your home, head to our guide to heat pumps vs. boilers for the full lowdown.
