Multi-split
Multi-split air conditioning for an apartment: when it is worth it
When the living room and two bedrooms need cooling and there is one balcony, a multi-split looks obvious. Sometimes it is; sometimes two separate units are cheaper, more reliable and more efficient.
4 min readUpdated
What a multi-split is
One outdoor unit connected to 2–5 indoor units (wall, cassette, ducted or floor), each with its own control. The outdoor unit is larger than a single split and each indoor unit has its own pipe run.
When it is the right choice
One possible outdoor location, building rules limiting outdoor units, a clean facade, rooms within 15–20 m of the outdoor unit. Typical: living room 12000 BTU plus two bedrooms at 9000 BTU on a 24000–27000 BTU outdoor unit.
When separate units are better
With space for two outdoor units, separate systems are usually 10–20% cheaper, more efficient and fault-tolerant. A multi-split also cannot cool one room while heating another.
Cost
Installation by our tariff: 76 € for an 18000–35000 BTU outdoor unit (102 € above 36000 BTU) plus 127 € per indoor unit with 3 m of pipework; extra pipework 30 €/m. Living room plus two bedrooms: 76 + 3 × 127 = 457 € with standard runs.
Sizing and brands
Add the indoor capacities and pick an outdoor unit rated at 80–100% of the sum; makers allow up to 130% because rooms rarely peak together. All Japanese brands have multi ranges (Daikin MXM, Mitsubishi Electric MXZ, Fujitsu AOYG, Toshiba RAS, Mitsubishi Heavy SCM); Gree and Kaisai offer value Free Match series.
Frequently asked questions
Can I add an indoor unit later?
Yes, if the outdoor unit has spare capacity and a free port. A pipe run can be pre-installed to the future room.
If the outdoor unit fails, do all rooms stop?
Yes, that is the main drawback. For a home heated mainly by the system, consider separate units or a backup source.
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