Multi systems are designed to accommodate multiple indoor units connected to a single outdoor unit. Each unit can be independently controlled, however, there may be limitations in the number of units connected and the capacity of the units connected to different outdoor units. When looking at a multi system, you should consider how the units will be operated. Will they be all running at one time or will you be using different units at different times? Multi systems will operate in cooling or heating (however you cannot have indoor units in different modes at the same time).