The Fantech DBF dryer exhaust fan is a smart and powerful solution for your dryer installation. This product is sturdy and protected in galvanized metal housing, and includes a 5 ft. long power cord for stress free installation. According to dryer manufacturers and some local building codes, duct booster fans should be added in the dryer duct run when the length of the duct exceeds 25 ft. with no bends, 20 ft. with 1 bend or 15 ft. with 2-bends. The Fantech dryer exhaust fans have been specially designed to solve the problems caused by long duct runs on clothes dryers. When the dryer is on, Fantech's patented pressure sensing switch automatically turns the exhaust fan on. The warm, moist air in the dryer duct is exhausted out of the building quickly.