Wall Mounted Air Conditioning Units
The wall-mounted split system is the standard fitted air conditioning for UK homes: a slim indoor unit high on the wall, a condenser outside, and a small pipe run between them. It costs £1,500 to £3,000 supplied and fitted, cools a room properly where portables struggle, and most models heat efficiently in winter too.
Quick Answer
A wall mounted air conditioning unit costs £1,500 to £3,000 supplied and fitted in the UK. It is a split system: a quiet indoor unit on the wall connected to an outdoor condenser. Installation takes about a day and must be done by an F-Gas certified engineer. Most models also heat in winter.
Fact-checked by John Rooney, Solar Energy Editor. Editorial policy
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How a wall-mounted split system works
Two halves make the system. The indoor unit, mounted high on the wall, draws room air across a cold coil and blows it back out chilled. The outdoor condenser does the noisy work of compressing refrigerant and dumping the extracted heat outside. Insulated pipes and a cable connect the two through a small hole in the wall, so the room stays sealed: no open window, no hose, unlike a portable. Run in reverse in winter, the same refrigerant loop pulls heat from outdoor air and releases it indoors, which is why these units are technically air-to-air heat pumps.
Want several rooms done? A multi-split feeds 2 to 5 indoor wall units from one outdoor condenser. The home air conditioning guide compares all the system types.
What wall-mounted units cost
| Item | Typical Price |
|---|---|
| Unit (indoor + outdoor) | £600 to £1,400 |
| Installation by F-Gas engineer | £700 to £1,200 |
| Total, single room | £1,500 to £3,000 |
| Multi-split, 2 to 3 rooms | £4,000 to £8,000 |
Capacity, brand tier and pipe-run length move the price within those ranges; London runs 15 to 25% above the national average. The cost guide breaks down every factor, and the installation guide covers what happens on fitting day.
Which brands do installers fit?
Daikin
Premium Japanese standard; quiet, efficient, widely supported by UK installers.
Mitsubishi Electric
The other premium default, known for reliability and very quiet indoor units.
Midea and value brands
Meaningfully cheaper units doing the same core job; a common way to land at the lower end of the fitted range.
A good installer will quote a brand and explain why. Comparing quotes across installers is also how you compare brand options: ask each what they would fit in your room and what the warranty difference is.
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A portable costs £250 to £700 with no installation, but it sits in the room with you at a noise level that spoils sleep, needs a hose out of an open window, and loses much of its own cooling to the heat that leaks back in. A wall-mounted split seals the room, moves the compressor outside, delivers 3 to 4 kW of cooling per kW of electricity, and heats in winter. If you cool a room more than a couple of weeks a year, the fitted unit wins on comfort and running cost.
Wall-Mounted Aircon FAQ
How much is a wall mounted air conditioning unit?
The unit itself costs £600 to £1,400 depending on brand and capacity, and installation adds £700 to £1,200, for a typical total of £1,500 to £3,000 supplied and fitted. A multi-split covering 2 to 3 rooms costs £4,000 to £8,000.
Can I fit a wall mounted air conditioner myself?
No. Split systems contain fluorinated refrigerant, and UK law requires F-Gas certification to install them. Self-installing also voids most manufacturer warranties. Only portable units are a genuine DIY option.
Are wall mounted air conditioning units noisy?
The noisy part, the compressor, lives in the outdoor unit. Modern indoor wall units are quiet enough for bedrooms, with night modes on decent models running at library-quiet levels. This is the biggest comfort difference from portable units, which keep the whole machine in the room with you.
Do wall mounted units heat as well as cool?
Most modern splits are air-to-air heat pumps: run in reverse they deliver roughly 3 to 4 kW of heat per kW of electricity, making them one of the cheapest ways to heat a single room in winter.
How long does fitting take?
About a day for a single room: mounting both units, connecting insulated refrigerant pipework and cabling through a small wall hole, pressure-testing and commissioning. There is no hose and no open window afterwards; the room stays sealed.
Where does the outdoor unit go?
On an outside wall, flat roof or at ground level, kept close to the indoor unit for a short pipe run. Installers position it away from neighbours' windows and consider noise and servicing access. Rules differ for flats, listed buildings and conservation areas, which your installer will check.
Sources
Last updated: September 2026
John Rooney is the founder of Solar Info and has been covering the UK solar energy market since 2023. He researches every battery and inverter brand against manufacturer datasheets, MCS and Ofgem data, and feedback from the MCS-certified installers in our directory before publishing.
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