Dryer vent fans, also called dryer booster fans, increase airflow, shorten drying times and prevent lint buildup in dryer ductwork. Dryer boosters are recommended and may be required, depending on local building codes, when ductwork exceeds 25 feet or 10 feet with three or more bends.
Most booster fans are mounted in the existing ductwork and must be at least 15 feet from the dryer to prevent lint from clogging the fan blades. Some models, such as the Tjernlund residential capacity dryer duct booster, are designed to repel lint while maintaining full airflow. Wall-mounted booster fans and external lint traps are used when ductwork is inaccessible.