The basic functional principle of drying dehumidifier is really quite simple. A fan draws in humid air and carries it through a refrigerated evaporator. The air is cooled well below its dew point. The water condenses on the cold surface of the evaporator and drips into a water container or is led directly to a drain. Then the cold dry air continues through a hot condenser which heats it up and returns it to the room to pick up new humidity. This procedure is continued until the desired condition is achieved.