A multisplit is an external motor that can be connected to several internal units, which can be, without distinction, wall-mounted, floor-mounted, ceiling-mounted, ductable and cassette. The multisplit units, each with its own effective yield and maximum connectable power, are classified according to the number of attacks in:

- dualsplit if they have 2 connections or 2 ports;
- trialsplit if they have 3 ports or 3 ports;
- quadrisplit if they have 4 attacks or 4 doors;
- pentasplit if they have 5 attacks or 5 doors;
- hexasplit if they have 6 attacks or 6 doors.

But how do you determine which multisplit is most suitable for air conditioning an apartment or an office?
First of all, it is necessary to establish the number of environments (or rooms) to be air-conditioned, calculate the kilowatts (kW) necessary for each of them (see thermal dimensioning) and, finally, group the same environments according to the presumable simultaneous use of the splits (e.g. living area and sleeping area).

Let's consider, for example, that we want to air-condition 3 rooms of an apartment. Since it is 2 bedrooms and a living room, we will have that 2 of the 3 indoor units will generally be used at the same time. The kilowatts needed to air-condition these rooms are: 3.5 kW (living area), 2.5 kW and 2.5 kW (sleeping area). At this point, considering the simultaneity of use, the powers of the indoor units must be added: thus we will have 3.5 kW for the living area and 5.0 kW (2.5 + 2.5) for the sleeping area. By virtue of these data, a 5.4 kW trialsplit will be required with a maximum connectable power of 10.0 kW: in fact, both the maximum power used (5.0 kW) and the total power of the indoor units (8.5 kW ) are compatible with the outdoor unit values.

Instead, let's analyze a case in which the rooms to be air-conditioned are occupied during the same hours of the day, as in the case of an office.

In fact, let's consider that we want to air-condition 3 rooms in an office, each of which requires 2.2 kW for air conditioning. In this case it is necessary to respect the yield value considering that the total sum of the powers of the 3 splits is 6.6 kW (2.2 + 2.2 + 2.2). In the light of these data, therefore, a 6.8 kW trialsplit will be required with a maximum connectable power of 12.0 kW: the 6.8 kW output will, in fact, guarantee 100% use of the indoor units, even in case of simultaneous use of the 3 splits.

ATTENTION: it is essential that the sum of the kilowatts of all the indoor units never exceed the value of the maximum connectable power of the multisplit, just as it is essential that the total power of the indoor units, which are used at the same time, must never exceed the value of the surrender.