Multi-Split Air Conditioning

A multi-split system connects two or more indoor units to a single outdoor unit. Each room has its own indoor unit and its own control, so you can cool a bedroom, warm a study and leave the spare room off, all from one unit outside.

How a Multi-Split Works

Each indoor unit has its own refrigerant pipework running back to the outdoor unit, which adjusts its output to match the rooms that are running. Depending on the model, one outdoor unit can serve between two and six indoor units. Mitsubishi Electric's MXZ range goes up to six rooms, and Panasonic and Toshiba ranges go up to five.

The indoor units do not all have to be the same type. A multi-split can combine wall units in the bedrooms with a floor-standing console in a loft room or a ceiling cassette in a kitchen extension.

Multi-Split or Separate Systems?

For two or three rooms, you can choose one multi-split or a separate single-split system for each room. Both are good solutions, and the right choice depends on your home.

Reasons to choose a multi-split

• One outdoor unit. Useful where outside wall space is limited, such as on a terraced house, or where you want to keep the outside of the house tidy.

• One electrical supply for the outdoor unit.

• Mix and match indoor unit styles and sizes to suit each room.

Reasons to choose separate systems

• Independence. If one system develops a fault, the other rooms keep running. With a multi-split, a fault with the outdoor unit affects every room.

• Heating and cooling at the same time. All the indoor units on a standard multi-split run in the same mode, either all heating or all cooling. Separate systems let one room cool while another heats.

• Efficiency. A single-split system matched to one room is usually more efficient. Mitsubishi Electric rates the MSZ-LN25 at a SCOP of 5.2 on its own outdoor unit, while its multi-split combinations are typically rated between 4.0 and 4.7.

• Shorter pipe runs. Each outdoor unit can sit close to the room it serves.

Planning a Multi-Split System

We start with a survey of each room: its size, which way it faces, how it is used and where the pipework can run. We then size each indoor unit for its room and choose an outdoor unit that can serve them all. Pipe runs are planned to be as short and neat as possible, often through the loft or along a single external route.

Each manufacturer sets maximum pipe lengths and height differences between the outdoor unit and each indoor unit, and we design every system within them.

What Does a Multi-Split Cost?

As a guide, multi-room systems usually range from £5,000 to £10,000+, depending on the number of rooms, the indoor unit types and the pipe routes. One room typically starts from around £2,500. We give you a clear written quote after a free survey. Our guide to air conditioning costs explains each factor.

Frequently Asked Questions

Can I add another room later?

Sometimes. If the outdoor unit has a spare connection and enough capacity, another indoor unit can be added later. If you think you might add a room, tell us at the survey so we can plan for it.

Can every room run at once?

Yes. The outdoor unit is sized for realistic use. If every room calls for full output at the same moment, the capacity is shared between them, and we allow for this when we design the system.

Does a multi-split heat as well as cool?

Yes. Every room can be heated in winter and cooled in summer, as long as all the rooms are in the same mode at the same time. See how air-to-air systems heat a home.

Is a multi-split noisy?

The indoor units are as quiet as single-room models. See our guide to the quietest air conditioners.

How many bedrooms can I cool?

Up to five or six rooms from one outdoor unit, depending on the model. Our bedroom air conditioning guide covers sizing and unit position for bedrooms.

Call 01772 288651 or use the form below to book a free survey. We will measure the room, recommend the right system and give you a clear written quote.

Last updated: November 2026.