Experts all agree that radon is everywhere. A naturally occurring radioactive gas, Radon in low concentrations is harmless. In today's better insulated homes however, radon can accumulate to harmful levels. Every Fantech Radon Fan is fully caulked as necessary to ensure optimum performance and durability. All fans are UL rated for outside installations.Fantech HP Series Fans Meet the Challenges of Radon Applications:HOUSING UV resistant, UL listed durable plastic UL Listed for use in commercial applications Factory sealed to prevent leakage Watertight electrical terminal box Approved for mounting in wet locations - i.e. OutdoorsMOTOR Totally enclosed for protection High efficiency EBM motorized impeller Automatic reset thermal overload protection Average life expectancy of 7-10 years under continuous load conditionsRELIABILIT