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Multi-Split Size Calculator
Size a multi-split air conditioning system correctly. Enter the total area of all rooms, the number of indoor units, and insulation quality to determine the right outdoor unit capacity.
How to Size a Multi-Split System
A multi-split system connects multiple indoor units to a single outdoor unit. The outdoor unit capacity doesn't need to equal the sum of all indoor units — it can be sized with a diversity factor since not all rooms will be used at peak load simultaneously.
However, for residential applications, it's safest to size the outdoor unit at 110% of the total calculated load to ensure adequate capacity when all zones call for cooling at once.
Each indoor unit should be sized for its individual room using the standard 100–150 W/m² rule.
Frequently Asked Questions
Can the outdoor unit be smaller than the total indoor units?
Yes, with a diversity factor. If not all rooms are used simultaneously, the outdoor unit can be 80–90% of the total indoor capacity. For residential use, 100–110% is recommended.
How many indoor units can one outdoor unit support?
Most residential multi-split outdoor units support 2–5 indoor units. Commercial VRF systems can support dozens of indoor units on a single outdoor unit.
What is the maximum pipe length for multi-split?
Typical multi-split systems allow 15–25 m per indoor unit with a total combined length of 50–75 m. Check the manufacturer's specifications for exact limits.
Multi-Split Size Calculator
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