Single Split vs Multi Split Air Conditioning: Which Does Your Home Need?
Single Split vs Multi Split Which Air Conditioning System Does Your Home Need?
Once you've decided on fixed air conditioning, the next question is how many outdoor units you'll end up with. A single split and a multi split use the same indoor units and give the same comfort in the room. The difference is in what sits outside, how the pipes run and what happens if something goes wrong.
A single split is one indoor unit connected to its own outdoor unit, and it's the right choice for one room or for rooms that are far apart. A multi split runs several indoor units from one outdoor unit, and it suits homes that want two or more rooms done where outside space is limited. Single splits are simpler and fully independent. Multi splits save outside wall space, but every room depends on the same outdoor unit.
What Is a Single Split?
A single split is the simplest type of fixed air conditioning. One indoor unit, usually mounted high on a wall, is connected by a pair of insulated copper pipes and a cable to one outdoor unit. The two halves work as a matched pair, and nothing else depends on them.
Want a second room done later? You add a second single split, with its own outdoor unit.
What Is a Multi Split?
A multi split connects two or more indoor units to a single outdoor unit. Each indoor unit has its own pipe run back to the outdoor unit, its own controller and its own temperature setting, so the bedroom can sit at 18°C while the lounge is at 21°C.
Panasonic's Free Multi range, for example, covers outdoor units for two rooms up to five rooms, and the indoor units don't have to match. You can combine wall-mounted units with floor consoles, ceiling cassettes or ducted units on the same system.
Single Split vs Multi Split at a Glance
| Single Split | Multi Split | |
|---|---|---|
| Outdoor units | One per room | One for several rooms |
| Rooms served | One | Typically two to five |
| Outside wall space | More, with every room added | Less, one unit to find a home for |
| Pipe runs | One short run, usually straight through the wall | One run per room, all leading back to the same point |
| Room-by-room temperature | Yes | Yes |
| Heat one room, cool another | Yes, the systems are independent | No, all rooms share one mode |
| If the outdoor unit fails | Only that room is affected | Every connected room is affected |
| Efficiency with one room running | Outdoor unit is matched to that room | Outdoor unit is larger than one room needs |
| Adding rooms later | Easy, add another system | Only if a spare connection was allowed for |
| Installation | Simpler and quicker | More planning, longer pipe routes |
Outdoor Unit Placement
This is usually what decides it. Every outdoor unit needs a solid base or wall brackets, clear airflow in front and behind, a route for the pipework, somewhere for condensate to drain, and enough distance from windows and boundaries that the noise doesn't bother you or next door.
On a detached house with a side passage, finding room for two or three small outdoor units is rarely a problem. On a terrace with a small rear yard, or a flat with a single balcony, it often is. That's where a multi split earns its keep: one outdoor unit, one position to agree.
Bear in mind that a multi split outdoor unit is bigger and, at full output, louder than a small single split one. As an example from Panasonic's figures, its 2.5kW single split outdoor unit is listed at 46 dB(A) in cooling, and its five-room outdoor unit at 53 dB(A). One larger unit is still usually easier to site well than three small ones, but it deserves the best spot you have. Planning rules can also come into it, particularly for flats and listed buildings, so we check that at survey.
Pipe Runs
Every indoor unit needs its own pipes back to the outdoor unit. With a single split you can normally put the outdoor unit directly behind or below the indoor unit, so the run is short and mostly hidden.
With a multi split, every room's pipework has to reach the same place. In a house that can mean runs through the loft, down an outside wall in trunking, or boxed in through a room. That's all normal, but it needs planning so it looks tidy when it's finished.
There are also hard limits set by the manufacturer. Taking Panasonic as the example, its datasheets allow 15 metres of pipe on the smaller Etherea single splits and 30 metres on the two largest. On its Free Multi outdoor units the limit is 20 or 25 metres to any one indoor unit depending on the model, with a cap on the total across all rooms that ranges from 30 metres on the smallest two-room unit to 80 metres on the five-room unit. There's a minimum of 3 metres per indoor unit as well. A survey confirms the routes fit within those limits before anything is ordered.
What Happens If the Outdoor Unit Fails?
The compressor, the main circuit board and the outdoor fan all live in the outdoor unit. On a single split, a fault there takes out one room. On a multi split, it takes out every room connected to it until it's repaired.
The same is true of the refrigerant. A multi split is one sealed circuit shared by every room, so a leak on any one pipe run affects the whole system. Separate single splits are separate circuits.
Outdoor unit failures aren't common on well-installed, well-maintained equipment, so this shouldn't put you off a multi split. It does matter more if air conditioning is your main heating, or if someone in the house relies on a cool bedroom for health reasons. In those cases it can be worth keeping one important room on its own single split. Either way, an annual air conditioning service is the best protection.
When Each One Fits
Choose a Single Split If
- You only need one room cooled or heated
- The rooms you want done are at opposite ends of the house
- You have plenty of outside space for more than one unit
- You want each room fully independent, including its mode
- You're starting with one room and may add others over time
- The room is your main heating and you want no shared risk
Choose a Multi Split If
- You want two or more rooms done at the same time
- Outside space is tight, or you want one unit out of sight
- The rooms are reasonably close together
- You're in a flat or terrace with one practical outdoor position
- You'd like to mix unit types, such as wall units and a ducted unit
- The rooms are mostly used at different times of day
Typical UK Home Scenarios
- One hot bedroom or loft room. Single split. There's nothing to gain from a larger outdoor unit.
- Home office or garden room. Single split. A garden room is usually too far from the house to share an outdoor unit sensibly.
- Three-bed semi, all bedrooms. A three-room multi split is the usual answer, with pipes run through the loft to one outdoor unit at the side or rear.
- Lounge downstairs and main bedroom upstairs. Either works. If one room is directly above the other, a two-room multi split is neat. If they're on different sides of the house, two single splits may mean less pipework on show.
- Flat with a balcony. Multi split, as there's normally only one place an outdoor unit can go. Check your lease and get the freeholder's consent first.
- Whole house, four or five rooms. Often a mix: a multi split for the bedrooms and a separate single split for the main living space, so the house is never left without any heating or cooling.
Whichever route you take, each indoor unit is sized for its own room. Our guide on what size air conditioner you need explains how. If you're weighing up which indoor unit to have, read our Panasonic Etherea review.
Common Questions
Is a multi split more efficient than several single splits?
Not automatically. A multi split outdoor unit is sized for several rooms, so it is working well below its capacity when only one room is on. Single splits are matched to their room. The difference is small in normal use, and for most homes the choice comes down to outside space and pipe routes.
Can a multi split heat one room and cool another?
No. All the indoor units share one outdoor unit, so they must all be in heating or all in cooling. Each room can still have its own temperature, or be switched off.
How many rooms can run off one outdoor unit?
It depends on the outdoor unit. Domestic multi split outdoor units are typically made for two, three, four or five indoor units.
Can I add another room to a multi split later?
Only if the outdoor unit was chosen with a spare connection and enough capacity. If you think you'll add rooms, tell us at survey so we can allow for it. With single splits, you simply add another system when you're ready.
Do the indoor units on a multi split have to be the same?
No. You can mix sizes, and with ranges such as Panasonic's Free Multi you can mix types too, for example wall-mounted units in the bedrooms and a ducted unit elsewhere.
Which is quicker to install?
A single split is the quicker and simpler job. A multi split takes longer because there are more indoor units and longer pipe routes to plan. Our air conditioning installation page explains what happens on the day.
Get a Free Survey
The right answer depends on your house, not on a rule of thumb. Our F-Gas certified engineers will look at where an outdoor unit can go, how the pipes would run and which rooms you use when, then recommend single splits, a multi split or a mix. We cover Dartford, Kent, Essex, Surrey and South East London. Call us on 01322 474 990.
Find out more about our air conditioning service.