Air conditioner for several rooms: multi-split or single-split units?
In short: There are two options for several rooms. A multi-split system supplies up to five indoor units from one outdoor unit, saving façade space, but all rooms depend on that one unit. Several single-split units each have their own outdoor unit; each room is independent and you can retrofit room by room. Multi-split fits when all rooms are planned now and space for outdoor units is limited.
Contents
The Two Paths
Anyone wishing to cool two or three rooms – such as a bedroom, a children’s room and a study – faces a choice: one outdoor unit for all rooms or one outdoor unit per room. Both approaches work. Which is more suitable depends primarily on the space available on the façade, the planning and whether all rooms are to be included straight away.
- Multi-split: One outdoor unit supplies several indoor units. According to the data sheet, Hantech’s multi-split outdoor units can accommodate up to two, three, four or five indoor units, depending on their size. Each indoor unit has its own refrigerant pipe to the outdoor unit; the pipes do not therefore run through a shared conduit.
- Multiple single-split units: Each room is fitted with its own set comprising an indoor and an outdoor unit. The units operate completely independently of one another.
Comparison
| Multi-Split | Multiple single-split | |
|---|---|---|
| Outdoor units | one | one per room |
| Space on the façade | fewer, but that one device is larger | more, the individual devices are smaller |
| If an outdoor unit fails | Are all rooms affected? | only one room is affected |
| Retrofitting | The number of indoor units is limited; it is better to plan everything together | an additional room at any time |
| Mixing devices | Indoor units must be compatible with the outdoor unit | every series, every brand per room |
| Power | is distributed across the rooms | Every room has its own full power rating |
Dimensions and weight
An example from the Hantech H-Pro series, according to the data sheet:
- The outdoor unit of a single-split set with 9,000 or 12,000 BTU measures 712 × 459 × 276 mm and weighs 22 kg.
- The multi-outdoor unit for two indoor units measures 835 × 605 × 360 mm and weighs 34 kg.
- The multi-outdoor unit for three indoor units measures 968 × 655 × 375 mm and weighs 46 kg.
Three rooms therefore require either three small units weighing a total of 66 kg or one larger unit weighing 46 kg, which, however, only requires a single installation point on the façade, on the balcony or on the ground. Where there is only one possible location for an outdoor unit, a multi-split system is the appropriate solution.
Performance and efficiency
In a multi-split system, the outdoor unit distributes its capacity amongst the indoor units in operation. The combined capacity of the indoor units may exceed that of the outdoor unit: the Hantech set, comprising two indoor units of 12,000 BTU each and an outdoor unit rated at 18,000 BTU, demonstrates this. If both rooms are running at full capacity at the same time, each receives less than a single 12,000 BTU unit would provide. This is suitable if the rooms are rarely cooled to full capacity at the same time, such as a bedroom at night and a study during the day.
In terms of efficiency, both options in the H-Pro series are very similar: according to the product data, the multi-sets have a SEER of 6.1 to 6.2 and a SCOP of 4.0, whilst the single-sets have a SEER of 6.1 to 6.5 and also a SCOP of 4.0. What these figures mean in terms of electricity consumption is explained under ‘How much electricity does an air conditioner use?’.
The power required for a room is specified under ‘Which air conditioner for which room size?’.
Outdoor noise level
A multi-outdoor unit is noisier than a single small one, but it is still just one unit. In the H-Pro series, the data sheet specifies a sound power level of 60 dB(A) for the outdoor unit of a single-set with 9,000 or 12,000 BTU, 65 dB(A) for the multi-outdoor unit with two indoor units, and 68 dB(A) for the one with three indoor units. Two units of the same noise level in the same location together produce around 3 dB(A) more than a single unit. You can find out more about these figures under ‘How loud is an air conditioner?’.
Planning and Installation
- Plan all rooms together: With multi-split systems, the outdoor unit determines how many indoor units can be added and what capacities they can have. Anyone wishing to add another room later will need a free connection for this.
- Piping routes: Each indoor unit requires its own pipe to the outdoor unit. Where rooms are far apart, the routes become long; the permissible lengths and height differences are specified in the outdoor unit’s data sheet.
- Operating mode: Check the manual to see whether the indoor units can operate in different modes simultaneously, i.e. whether one room can be cooled whilst another is being heated.
- Specialist contractor: Both methods must be carried out by a certified specialist contractor, who will install the refrigerant pipework and commission the system. Information on how we verify this can be found under ‘Professional installation of your air conditioner’.
What sets are available
The following ready-made multi-split sets with wall-mounted units are currently available: Hantech H-Pro with two, three or four indoor units of 9,000 BTU each and with two of 12,000 BTU each, plus TCL BreezeIN with two or three indoor units of 9,000 BTU each (as at October 2026). All multi-split systems can be found under ‘Multi-split air conditioners’, whilst single-split sets are listed under ‘Split air conditioners’.
Multi-split air conditioners
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