Split air conditioners in the UK: what they are and what they cost
By Dale @ ukaircontracker · facts checked
Quick answer
A split air conditioner has two parts: a wall-mounted indoor unit and an outdoor condenser, joined by refrigerant pipes through a small hole in the wall. In the UK a single-room split system typically costs £1,500–£2,500 installed. A 2.5 kW unit draws roughly 0.6–0.8 kW, about 18p an hour at the current price cap, and most also heat.
| Type | Rooms | Typical installed cost | Notes |
|---|---|---|---|
| Single split (wall-mounted) | 1 | £1,500 – £2,500 | One indoor unit, one outdoor unit, short pipe run |
| Multi-split | 2 – 5 | £3,000 – £5,500 (2–3 rooms) | Several indoor units on one outdoor unit |
| Ceiling cassette | 1 large room | Higher than wall-mounted | Needs a ceiling void; common in offices and open-plan rooms |
| Ducted | Whole floor or house | £5,000 – £9,000+ (whole house) | Hidden unit, grilles in each room; needs loft or ceiling space |
Ranges are the typical UK figures we use across the site; your quote depends on pipe length, wall construction, electrics and access.
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How a split system works
The indoor unit pulls warm room air across a cold coil, and the refrigerant carries that heat through insulated pipes to the outdoor unit, which releases it outside. Because the noisy compressor sits outdoors, a split system is far quieter indoors than a portable air conditioner, and there is no hose hanging out of a window.
Most split systems sold in the UK are reversible (sometimes called air-to-air heat pumps), so the same unit heats in winter. That year-round use is the main reason people choose a fitted system over a portable one.
Running cost
At 26.32p/kWh, a split unit drawing 0.7 kW costs about 18p an hour at full output. A typical portable air conditioner draws 0.8–1.3 kW (21p–34p an hour) for less cooling, because it heats some of the air it is trying to cool through its own casing and hose.
Who can install one
Connecting the refrigerant circuit is regulated. Under the F-gas rules, the person who installs, services or decommissions the system must hold the right F-gas certificate, so a split system is not a DIY job. Ask any installer for their F-gas certificate number before you book.
- Check whether the outdoor unit needs planning permission at your property (see our planning permission guide).
- Renters need the landlord's written consent; a portable unit is the usual alternative.
- Ask for the pipe-run length in the quote; long runs cost more.
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Common questions
- What is the difference between a split air conditioner and a portable one?
- A split system has an indoor and an outdoor unit joined by refrigerant pipes and must be fitted by an F-gas certified installer. A portable unit sits in the room and vents hot air through a hose. Split systems are quieter, cool better and usually heat too; portables cost less and need no installation.
- How much does a split air conditioner cost in the UK?
- A single-room wall-mounted split system typically costs £1,500–£2,500 installed. Multi-split systems for 2–3 rooms typically cost £3,000–£5,500.
- Can a split air conditioner heat a room?
- Most split systems sold in the UK are reversible and heat as well as cool. In heating mode they deliver several units of heat for each unit of electricity, which is why they are often cheaper to run than plug-in electric heaters.
- How long does a split system take to install?
- A single wall-mounted split system is usually fitted in a day. Multi-split and ducted systems take longer.