Multi splits allow a combination of KW sizes to connect to the outdoor unit.
Some brands allow up to 8 indoor units to be run off one outdoor unit. What you need to do is very simple when deciding what size outdoor unit you will need.
2 x 2.5 kw indoor units will need a 5.0 kw outdoor unit
3 x 2.5 kw indoor units will need around 7.5kw outdoor unit
1 x 2.5 indoor and 1 x 5.0 kw indoor will need around 7.5 kw outdoor unit
Also, if you were to use 4 x 2.5 kw indoor units to service 4 bedrooms you could use an 8.0kw outdoor unit
But 4 x 2.5kw = 10kw…… I hear you say.
If all 4 units are running at their maximum capacity, the outdoor unit will give each unit only 2.0kw of output. But generally speaking, the indoor units are rarely running at full capacity. Plus, you may only need to run 3 units most of the time. Maybe the 4th unit is in a spare room and only need from time to time.
Particularly handy for people who live in apartments and literally don’t have space for any more than one outdoor unit.
If this happens in summer, having separate units will mean you will at least have air conditioning units working while waiting for a service.