Heatmax's fan coil, which is the indoor unit of an air conditioning system, transfers heat or cooling to the space by supplying water at the appropriate temperature. In Greek, it is referred to as a forced air circulation unit.

Its operation is based on the forced circulation of air created by the fan it has. With the help of the fan, heat is dispersed into the room, unlike simple radiators where heat distribution occurs naturally through convection. It can be connected to a heat pump or boiler to provide heating and cooling throughout the year.

The unit is installed on the ceiling of the space, embedded in a false ceiling, but it can also be installed freely if aesthetics are not a concern. Air extraction is only from the point where the unit is installed, unlike ducted air conditioners where multiple air outlet points can be installed.