Can Air Conditioning Heat Your Home? Air-to-Air Heat Pumps Explained
Yes. Most modern split air conditioning systems can heat as well as cool. A reverse-cycle air conditioner is an air-to-air heat pump. In heating mode it takes heat from the outside air and blows warm air into the room.
It can be a very efficient way to heat individual rooms. But it doesn’t heat water, so it can’t give you hot taps or showers. In most UK homes it works best alongside existing heating, or in rooms such as a home office, conservatory or loft conversion, rather than as a direct replacement for a boiler.
How it works
The outdoor unit and the indoor wall unit are connected by refrigerant pipes. In cooling mode, heat is moved out of the room. In heating mode, the system reverses and moves heat from outside air into the room, even when it’s cold outside.
Because it moves heat instead of making it, an air-to-air heat pump can deliver several units of heat for each unit of electricity it uses. Manufacturers show this as a seasonal efficiency rating (SCOP) for heating. The higher the number, the cheaper it is to run.
Air conditioning vs gas central heating
| Air-to-air (air con) | Gas boiler + radiators | |
|---|---|---|
| Heats rooms | Yes. Warm air from wall units | Yes. Radiators |
| Hot water | No | Yes (combi, or a boiler with a cylinder) |
| Cooling in summer | Yes | No |
| Fuel | Electricity | Gas |
| Coverage | Room by room (one indoor unit per room) | Whole house |
| Best use | Individual rooms, extensions, offices, top-up heating | Whole-home heating and hot water |
Whether it’s cheaper than gas depends on the system’s efficiency, your electricity and gas tariffs, and how well insulated the room is. A good installer should give you realistic running cost estimates for your home, not a guaranteed saving.
How much does it cost?
According to Checkatrade (updated May 2026):
| System | Typical installed cost |
|---|---|
| Single split, one room (12,000 BTU) | £1,480–£2,270 |
| Ducted system (12,000 BTU) | £2,290–£3,290 |
| Portable unit (no installation) | £300–£420 |
| Running cost | Around 20p–60p per hour |
| One-off service | £70–£120 per unit |
Multi-split systems, with one outdoor unit serving several rooms, cost more overall but usually less per room. Checkatrade notes that a single unit is usually fitted in about a day, and a multi-room system can take closer to a week.
Portable units are cheap, but they’re much less efficient and noisier than a fixed split system. They’re best kept for occasional cooling.
Is there a grant?
Yes, in some cases. The Boiler Upgrade Scheme in England and Wales now includes a £2,500 grant for air-to-air heat pumps, according to Ofgem (September 2026). The usual scheme rules apply: it must replace fossil fuel heating, be installed by an MCS certified installer, and be sized to meet the property’s heating needs. That means a single unit added as top-up heating in one room usually won’t qualify.
Here’s the full guide to who qualifies for the Boiler Upgrade Scheme.
Who can install it?
Air conditioning and air-to-air heat pumps contain refrigerant gases. Anyone handling those gases must hold the correct F-Gas certification, and the business should be F-Gas certified too. Ask to see proof before you book. If you want the Boiler Upgrade Scheme grant, the installer must also be MCS certified.
The electrical connection must meet the wiring regulations, and it’s usually done by the installer or their electrician.
Planning permission
Many domestic air conditioning and heat pump installations count as permitted development, but there are conditions. These include how close the outdoor unit is to the boundary, noise levels and where it’s mounted. The rules for listed buildings, flats and conservation areas are different, and they have changed in recent years. Check with your installer or local council before committing.
Does it need servicing?
Yes. An annual service keeps it running efficiently and protects the warranty. A service typically covers cleaning the filters and coils, checking refrigerant levels and pressures, and checking the condensate drain and electrics. You can usually clean the indoor filters yourself between services. Check the manual for how.
FAQs
Is heating with air conditioning expensive?
Not necessarily. A good split system in heating mode can be efficient, because it moves heat instead of generating it. Portable units and old systems cost much more to run.
Can air conditioning replace my boiler?
Only if you have another way to heat water, such as an electric cylinder or a separate water heater, and enough indoor units to heat every room. For most homes, an air-to-water heat pump is the more common way to replace a boiler.
Does air conditioning work in winter?
Yes. Modern units keep heating in sub-zero temperatures, although efficiency drops as it gets colder. Check the manufacturer’s operating range.