These Duct Booster fans from Tjernlund Products are designed to boost airflow to hard-to-heat or cool rooms or exhaust foul air from a bathroom or pole barn. According to the company, many homeowners live with rooms that are uncomfortably hot or cold because the fan in their forced-air furnace cannot provide adequate velocity. Tjernlund Products offers a family of Duct Booster fans designed for installation within heating and cooling ducts to increase flow of conditioned air to desired areas. The company also says its Duct Booster fans operate quietly and are built to provide years of trouble-free service. There are models of varying capacities for installation in metal and flex ductwork. Optional accessories are available for automatic activation and to control fan speed.

Tjernlund Products, 1601 Ninth St., White Bear Lake, MN 55110-6794; (800) 255-4208; www.tjernlund.com.