Components / Air-conditioning hardware / Single-split and multi-split air conditioning

C-045·Components / Air-conditioning hardware

Single-split and multi-split air conditioning

The practical differences between one-to-one and shared-outdoor-unit split systems.

A single-split system connects one indoor unit to one outdoor unit. A multi-split system connects several permitted indoor units to one compatible outdoor unit.

The choice changes the equipment layout, refrigerant network and way capacity is shared. It does not establish which option is more efficient, cheaper, quieter or better suited to the property.

Multi-split systems

A multi-split uses one outdoor unit for several indoor units. The indoor units may be available in different formats, such as high-wall, floor-console, cassette or concealed ducted, subject to the manufacturer’s compatibility data.

The shared outdoor unit can reduce the number of external units. The connected indoor units depend on that outdoor unit and use a more extensive refrigerant network than a single split.

Multi-split controls need checking at product level. Individual indoor units may have separate room set points, but that does not mean every room can select heating or cooling independently. On the checked Daikin multi-split platform, connected indoor units must use the same heating or cooling mode. Other platforms may use different control rules.

Capacity and permitted combinations

The model names on indoor units do not show the output available when they share an outdoor unit. Manufacturer selection data covers:

  • the indoor units that may be connected
  • the permitted total connected capacity
  • the capacity available to a particular combination
  • diversity and simultaneous operation
  • product-specific control restrictions

The selected combination must be assessed from this data. Adding the indoor-unit labels does not establish the outdoor capacity available to them.

MCS 031 b distinguishes single-split and multi-split systems in its pre-sale performance presentation. The system records still need the exact combination rather than only a family name.

System combination data

A valid single-split or multi-split combination is defined by:

  • exact indoor and outdoor model codes
  • the manufacturer’s approved combination
  • output available to the combination
  • connected-capacity and diversity information
  • simultaneous-operation assumptions
  • heating and cooling mode restrictions

An outdoor-unit label on its own leaves out the connected indoor units and the way capacity is distributed.

Applies to

Heat

Last reviewed

28 Jul 2026