Patent attributes
A fan unit being suspended from a building floor structure within a crawl space. The fan unit includes a fan, a fan motor, an inlet grill, a discharge plenum and an outlet grill. A timer connected in the power supply activates the fan motor at periodic predetermined time intervals to move the crawl space air through the fan unit. The fan unit is located and orientated to create a negative pressure to pull air into the crawl space through wall inlet grills and to also create a positive pressure to force air out of the crawl space through wall outlet grills. An outside humidity sensor can be used to insure the outside air has a lower percent humidity than that desired in the crawl space and an inside humidity sensor is used to turn the fan unit off if the crawl space humidity is below an acceptable limit.
