Set this Five-Function Wall Control by Fantech to low, medium or high speed to control the ventilation in your house. Install in a central location and keep the air around you clean and fresh. The dehumidistat control is ideal for use in energy-efficient houses, allowing you to keep the humidy down in order to avoid any structural damage and keep mold and mildew to a minimum. This unit has an override timer, which will provide high speed ventilation for one 15, 30 or 60 minute period. The digital display shows the indoor humidity level and it has a maintenance light that comes on when the unit needs to be cleaned.