Once you've decided to have air conditioning fitted, the next question is nearly always the same: one system per room, or one system for the house? It sounds technical, but the choice between split and multi-split air conditioning comes down to a handful of practical factors — how many rooms you're doing, how much outside wall you have, and whether you might add rooms later. Here's how we talk it through on surveys across Swindon, Chippenham, Devizes and the rest of Wiltshire.
A single split is the simplest setup: one indoor unit paired with one outdoor condenser, connected by refrigerant pipework. The indoor unit cools (and heats) one room; the condenser sits outside on a wall or the ground. It's the standard choice for a bedroom, lounge, home office or garden room, and it's what most people mean when they say "air conditioning unit". Installation is usually a single day.
A multi-split system runs two to five indoor units from one outdoor condenser. Each room gets its own indoor unit and its own remote or app control, but everything connects back to a single box outside. You choose the indoor units room by room — a wall-mounted unit in the bedroom, a floor console under the landing window, a cassette in the open-plan kitchen — all on one system.
One room: single split, no contest. Two or more rooms today: multi-split usually wins on price and tidiness. The trap is the "one room now, maybe two more later" plan — a single-split condenser can never take a second indoor unit, so if you're likely to expand, it's worth fitting a multi-split condenser sized for the future from day one.
Every single split needs its own condenser outside. Three rooms as three singles means three boxes on your walls — fine on a detached house, awkward on a terrace in Trowbridge or Salisbury with one usable elevation. A multi-split puts one condenser outside no matter how many rooms it serves, which is often the deciding factor in town.
For two rooms, a twin multi-split usually comes in cheaper than two separate single splits — one condenser, one electrical supply, one day's pipework instead of two complete systems. As a rough 2026 guide, two single splits might total £3,200–£4,400 installed, where a twin multi-split typically lands at £2,800–£3,800. Full figures are in our installation cost guide.
The honest argument for two singles: if one system develops a fault, the other still works. On a multi-split, a condenser fault takes every room down at once. For most homes that's a minor risk worth taking for the saving — but if the rooms are, say, a home office you can't work without and a bedroom you can't sleep without, some people prefer the backup.
Every system has maximum pipe lengths between condenser and indoor units. On multi-splits there's a limit per room and a total across the system, so a sprawling bungalow may need the condenser positioned centrally — or two systems after all. This is exactly the kind of thing a survey settles in ten minutes.
Both setups give each room its own temperature and fan control. The one caveat on a multi-split: all rooms must run the same mode (all heating or all cooling) because they share one refrigerant circuit — see the FAQ below.
| Your situation | Usually best | Why |
|---|---|---|
| One room only, no plans to add more | Single split | Cheapest, simplest, one-day install |
| 2–4 rooms now | Multi-split | Cheaper than multiple singles, one condenser |
| One room now, more likely later | Multi-split (condenser sized ahead) | Add indoor units later without replacing kit |
| Limited outside wall space | Multi-split | One outdoor box serves the whole house |
| Rooms that must never be down together | Two single splits | Built-in backup if one system faults |
| Rooms far apart / long pipe runs | Survey decides | Pipe-length limits may force the layout |
Whichever way you lean, make sure each indoor unit is sized to its room — our guide to what size air conditioning unit you need explains how capacity is worked out.
The split-or-multi question is usually settled in one look at the property. Tell us your town, the rooms you want done and any you might add later, and send us a message — we'll come back the same working day and arrange a free survey with a fixed price for the right system.
Only if the outdoor condenser was sized for it from the start. A single-split condenser serves one indoor unit and can't take a second; a multi-split condenser has a fixed number of ports and a maximum capacity. If you think you might add a bedroom or office later, say so at the survey — fitting a slightly larger multi-split condenser now is far cheaper than replacing it in two years.
No. A multi-split system runs two to five indoor units from a single outdoor condenser, which is exactly why people choose it — one box outside instead of a row of them. Each room still gets its own indoor unit and its own temperature control.
Broadly, yes. On a standard multi-split every indoor unit must be in the same mode — all heating or all cooling — because they share one refrigerant circuit. Each room can have a different target temperature and fan speed, but one bedroom can't heat while the lounge cools. If that genuinely matters, two separate single splits solve it.
Tell us which rooms you'd like cooled or heated and your town — our local team will recommend the right system and come back with a fixed quote.
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