Air-to-air heat pumps
Air to air heat pumps: one system to heat and cool your home
An air to air heat pump warms your rooms in winter and cools them in summer, using a fraction of the electricity of a plug-in heater. Apex designs and fits them for homes and businesses across Dartford, Kent and south-east London, with a free survey and a fixed written quote from Olly himself.
The basics
What is an air to air heat pump?
It is a heat-and-cool air conditioning system. If you have heard both names, they are usually the same thing.
An outdoor unit draws heat out of the outside air, even on a cold day, and refrigerant carries it through two small pipes to an indoor unit, which blows warm air into the room. In summer the system runs in reverse: it takes heat out of the room and dumps it outside. That reversing trick is why one system does both jobs.
Because it moves heat rather than making it, a well-sized system gives out roughly three to four units of heat for every unit of electricity it uses.
- Heating and cooling from the same unit, switched on the remote or the app.
- Room by room control. One outdoor unit can run a single room or, on a multi-split, up to about five indoor units.
- Fast warm-up. Warm air reaches the room within minutes, with no radiators to heat first.
- Dehumidifies too. Cooling mode pulls moisture out of muggy summer air.
- No water, no flue, no gas. Just electricity, a pipe run and a condensate drain.
- Indoor unit choices: wall-mounted, floor-mounted in place of a radiator, or ducted out of sight.
Heating in winter
Can an air to air heat pump heat your home?
Yes, and for many people that is where it earns its keep. Hot summers last a few weeks; the heating season lasts months. Used for heating, an air-to-air system suits:
- Rooms that are hard to heat, such as loft conversions, extensions, conservatories and garden rooms.
- Homes on electric heating, such as flats with storage or panel heaters.
- Topping up a gas system, so you heat the rooms you use instead of the whole house.
- Workplaces, from a salon to an office, where one system covers the whole year.
Sizing matters more for heating than for cooling. We work out how much heat each room loses on a cold day, so the unit keeps up in January rather than just coping in July.
A photo of the room and the outside wall is often enough for a first idea.
Running costs
Air to air heat pump running costs vs electric heaters
A plug-in fan heater, oil-filled radiator or panel heater turns one unit of electricity into one unit of heat. An air-to-air heat pump moves heat in from outside, so each unit of electricity gives you roughly three to four units of heat. At the Ofgem price cap for October to December 2026 (26.32p per kWh), that works out like this. Our arithmetic, for the same amount of heat:
Swipe sideways to see the whole table →
| Heating type | Heat per unit of electricity | Cost per kWh of heat |
|---|---|---|
| Electric heater | 1 unit | about 26p |
| Air to air heat pump | about 3 to 4 units | about 7 to 9p |
Which? (July 2026) says air-to-air heating should cost less to run than other electric heating, but adds that using it for cooling will add to your annual energy use. Real costs depend on the weather, the insulation and the setting you choose. See our guide to air conditioning running costs for heating and cooling mode.
Choosing
Air to air vs air to water heat pumps
Both are air source heat pumps. The difference is what they heat. Air-to-air heats the air in a room directly. Air-to-water heats water for radiators or underfloor heating and a hot water cylinder, the way a boiler does.
Swipe sideways to see the whole table →
| Question | Air to air | Air to water |
|---|---|---|
| What it heats | Room air, through indoor units | Water, through radiators or underfloor |
| Hot water for taps | No | Yes, with a cylinder |
| Cooling in summer | Yes | Not usually |
| Disruption to fit | Lower: a pipe run per indoor unit | Higher: cylinder, often bigger radiators |
| Boiler Upgrade Scheme grant | £2,500, only via an MCS-certified installer | £7,500, only via an MCS-certified installer |
If you want summer cooling, or you are heating rooms rather than replacing a whole boiler system, air-to-air usually fits better. If you need one system for heating and hot water, air-to-water is the usual answer.
Planning
Do you need planning permission for an air to air heat pump?
Usually not, on a house in England. Since 29 May 2025, an air-to-air heat pump is normally permitted development, provided it is not used only for cooling and meets the rules:
- Noise: the outdoor unit must pass the MCS 020(a) calculation, 37 dB(A) at 1m from a neighbour's nearest door or window to a habitable room. We run it at the survey.
- Size and number: outdoor unit up to 1.5 cubic metres on a house; up to two units on a detached house, one on other homes.
- Position: not on a pitched roof, not within 1m of the edge of a flat roof, and in a conservation area not on a wall facing a road.
- Exceptions: listed buildings need consent, and flats usually need the freeholder's permission. See air conditioning in a flat.
The full picture is in our planning permission guide.
Grant
Is there an air to air heat pump grant?
Since 28 April 2026, air-to-air heat pumps can qualify for a £2,500 Boiler Upgrade Scheme grant in England and Wales (GOV.UK). It is not automatic. The main conditions:
- The installer must be MCS-certified for air-to-air heat pumps, and the installer applies for the grant.
- The heat pump must replace fossil-fuel heating such as gas, oil or LPG, which has to be removed.
- It must provide all the home's space heating, with hot water from a non-fossil source such as an electric immersion.
- One grant per property. Most new builds and social housing are excluded.
Adding cooling to a few rooms while keeping a gas boiler would not qualify. Also note that in April 2026 MCS said installers could not yet be certified for air-to-air systems, so check the current position on GOV.UK before you plan around the grant. We will tell you honestly whether it is realistic for your home.
Cost
How much does an air to air heat pump cost?
Published UK figures give a guide. Which? (July 2026) puts a single-room system at about £1,900 and a multi-unit system for a three-bedroom semi at about £3,700. The government quoted about £4,500 for a flat or small house when it announced the grant. More in our air conditioning cost guide.
What changes the price:
- The heat output each room needs, in kW
- How many indoor units, and wall, floor or ducted
- Pipe run length and where the outdoor unit can go
- Electrical supply and condensate route
Your survey is free, and the quote is fixed and in writing. See air conditioning installation for how we fit.
How we fit it
Getting an air to air heat pump installed
Free survey
Olly measures up, works out the heat loss and gain room by room, and checks the outdoor position and noise.
Fixed quote
The units, sizes, pipe route and outdoor position, in writing. No surprises on the day.
Fitted neatly
Usually a day for a single room, with dust sheets down and pipework in neat trunking.
Set up for heating
Commissioned, tested in heating and cooling, and the app set up the way you live.
After that, a yearly heat pump service keeps it efficient and keeps the manufacturer's warranty valid.
Our installs
Heat-and-cool systems we've fitted
Real Apex jobs, including a Panasonic home office system in Dartford that heats and cools the room.
Reviews
“Cool in the summer and warm in the winter”
Word for word from Checkatrade and Google.
Really pleased with the service provided, olly and his team done an amazing job fitting an air conditioning unit into my salon. It’s nice to know I can keep my clients cool in the summer and warm in the winter. Overall 10/10 service provided, will defiantly be recommending them and thinking about having another unit installed into my home.
Olly and Andy came to install Mitsubishi HI a 7kw and a 12kw multi-split units. Not a small job as we had 7 indoor units to hang and lots of awkward trunking /pipe runs in eves and suffixes. All in all, a very friendly and professionally installation. I am especially impressed with Olly who is very careful with the work and has a keen eye for detail - a part I highly recommend. Olly and Andy came with shoe protectors, dust sheets and mobile vacuums, keeping all things tidy and clean at all times. Not pushy and very accomodating with all our requirements. Highly recommended!
Had three units installed now and cannot fault either the equipment or Apex, from the initial unbiased advice, through to installation, I have no complaints whatsoever. Would recommend to anyone
Questions
Air to air heat pump FAQs
Is an air to air heat pump the same as air conditioning?
Very nearly. A modern air conditioning system that heats as well as cools is an air-to-air heat pump: the same outdoor unit, indoor units and refrigerant pipework, run in either direction. HMRC's guidance says most air conditioning units are air source heat pumps. A cooling-only unit is not, and it is treated differently for planning.
Can an air to air heat pump heat water?
No. It heats and cools the air in a room, and that is all. Your hot water still comes from a boiler, an immersion heater or another system. If you need a heat pump that also heats a hot water cylinder and radiators, that is an air-to-water heat pump, a different kind of system.
Do air to air heat pumps work in winter?
Yes. They are built to keep heating when it is cold outside, well below freezing on most current models, though output drops as the temperature falls. That is why we size for your coldest weeks, not a mild day. In cold, damp weather the outdoor unit defrosts itself every so often, which can look like steam. That is normal.
Are air to air heat pumps worth it?
They are strongest where you want cooling in summer and cheaper heat than plug-in electric heaters in winter: bedrooms, lofts, home offices, garden rooms, flats and extensions. They don't heat water, and the warm air feels different from a radiator. Whether a whole-home system beats your current heating depends on the house, and we'll tell you honestly.
Can you get a grant for an air to air heat pump?
Since 28 April 2026, the Boiler Upgrade Scheme offers £2,500 towards an air-to-air heat pump in England and Wales, but only when it replaces fossil-fuel heating, provides all the home's space heating, and is fitted by an MCS-certified installer who applies for it. In April 2026 MCS said installers could not yet be certified for air-to-air, so check the current position on GOV.UK before relying on it.
Are air to air heat pumps noisy?
Indoor units on a low setting are very quiet, quiet enough for bedrooms. The outdoor unit makes a steady hum, louder when it works hard. For planning, it must meet 37 dB(A) at your neighbour's nearest door or window, and we check that before fitting. Anti-vibration mounts and careful siting keep it out of earshot.
Get a free survey
Tell us the rooms and how you heat them now. Olly replies himself.
Quickest way to a price: send on WhatsApp
- A photo of the room and the outside wall
- Your town and what you need
- For a repair, the unit's label and any error code
Free survey and a fixed written quote for new systems. No obligation.