The preheater is used to maintain the temperature or humidity of fresh air at a preset level. The function prevents icing, overuse of the after heater and water condensation in the filters by preheating incoming fresh air.

The function controls water or electric heating coil placed in the intake duct of the air handling unit. The configuration steps for each preheater type are similar to heater configuration (water heater or electric heater).

A preheater can be used either for low limiting temperature of intake air (Preheating) or for controlling intake air saturation with water vapor (Filter drying).