Split vs Multi-Split vs Ducted Air Conditioning
One room, several rooms, or the whole house invisibly? The three main system types solve different problems at very different prices — from £1,500 for a single split to £15,000+ for ducted. Here's how to choose.
The three system types
All three are built from the same ingredients — an outdoor unit doing the heavy lifting and indoor units delivering conditioned air — arranged differently.
How each system works
Single split — one indoor unit (usually wall-mounted) paired with one outdoor unit. The default choice for cooling and heating one room: simplest install (often a single day), cheapest to buy, and if one system develops a fault, only that room is affected.
Multi-split — two to five indoor units running off one shared outdoor unit. You get individual temperature control per room with only one box outside — the deciding factor when outside wall space, planning constraints or aesthetics limit how many outdoor units you can mount. Pipe runs are longer and the install takes one to two days or more.
Ducted — a concealed unit (typically in the loft or a ceiling void) pushes conditioned air through insulated ducts to discreet ceiling grilles in each room. Nothing on the walls, near-silent in the rooms, whole-house coverage — at the highest price, and it needs the void space to run ducts, so it suits new builds, renovations, bungalows and homes with generous lofts.
Pros, cons and costs compared
| Single split | Multi-split | Ducted | |
|---|---|---|---|
| Installed cost (2026) | £1,500–£3,000 | £2,800–£5,000 (2 rooms) £4,500–£7,500 (3 rooms) | £7,000–£15,000+ |
| Rooms covered | 1 | 2–5 | Whole house / large zones |
| Outdoor units | 1 per room | 1 shared | 1 |
| Looks inside | Wall unit visible | Wall units visible | Grilles only — most discreet |
| In-room noise | Low (quiet modes near-whisper) | Low | Lowest — fan unit is remote |
| Room-by-room control | Full (independent systems) | Full (per indoor unit) | Depends on zoning design |
| Efficiency notes | Excellent; sized precisely to the room | Excellent; slight penalty on long pipe runs | Good, but duct losses and whole-zones running can cost more per room |
| Failure impact | One room | Outdoor unit fault affects all connected rooms | Fault affects the whole system |
| Disruption to install | Lowest — about a day | Moderate — 1–2 days | Highest — 3–5+ days, ceiling work |
Costs are UK supplied-and-installed ranges, 2026. Two single splits can rival a 2-room multi-split on price — which wins depends on wall space, planning and pipe-run practicalities, so get quotes for both options.
Which system suits your home or business?
- One warm bedroom or a home office — single split, no contest. Cheapest, quickest, and independently controlled.
- Two or three rooms, limited outside space — multi-split. One outdoor unit keeps the garden wall tidy and planning simpler; per-room cost falls as you add rooms.
- Flat or terrace with one usable outside wall — multi-split is often the only practical route to multiple rooms; freeholder/landlord consent applies either way.
- Whole-house comfort in a renovation or new build — ducted, designed in while ceilings are open, gives the most invisible, premium result.
- Design-led living spaces — ducted if the budget and voids allow; otherwise premium wall units (e.g. design ranges) keep things elegant.
- Small shop, office or restaurant — wall splits or ceiling cassettes; larger premises step up to VRF systems — see our commercial cost guide.
Aesthetics, noise and efficiency: the honest trade-offs
Ducted wins on looks and in-room silence but costs two to five times a simple system and is the hardest to retrofit. Multi-split trades a single tidy outdoor unit against the risk that one outdoor fault takes out every connected room, and very long pipe runs shave efficiency. Single splits are the efficiency and redundancy sweet spot but put a unit on the wall of every room and can multiply outdoor boxes — which neighbours, planners and leaseholders may care about. There is no universally best answer; there is a best answer for your building, and a good surveying engineer will often quote two configurations so you can compare.
One practical factor tips many decisions towards multi-split: the outdoor unit. In England a single outdoor air conditioning unit can often be fitted under permitted development if it meets the volume limit and siting rules, but a second unit — or any unit on a flat or in a conservation area — generally needs an application. So a multi-split serving several rooms from one box can be the difference between a form-free install and a planning submission. Our planning permission guide sets out the current rules in full.
Frequently asked questions
Sources & methodology
- Installed-cost ranges from UK installer quote data, 2026.
- System characteristics from manufacturer published specifications for current split, multi-split and ducted ranges.
Not sure which type? Let engineers advise
Air Con Surrey is a free matching service — we'll match you with vetted, F-Gas certified engineers who survey your home, recommend the right configuration and quote it properly, so you compare like for like.