Sensaire® technology detects rapid increases in moisture levels at the ceiling, where steam and humidity naturally rise. Regular humidistats located on the wall simply detect absolute humidity levels and are prone to false triggers, or not operating when they should. An automated solution to fight excess humidity and mold. Our humidity sensing fans turn on and off automatically to help prevent cosmetic and structural problems associated with excess moisture. Adjust the sensitivity level and run-time. Just beneath the drop-down grille are easy-to-adjust sensitivity and run-time controls. Choose your preference, set with a screwdriver and forget it. Of course, you can always override the sensor at the touch of a switch. Hands-free operation. Since you never have to worry about turning the fan on, Broan Ultra Silent™ is ideal for problem areas in residential, institutional and light-commercial applications. Our exclusive Sensaire® technology is a perfect solution for high-traffic bathrooms, or a kid's bathroom. It turns off automatically, and that saves money. Humidity sensing fans are ideal for anyone who leaves the house before humidity is properly vented. With a fan this quiet, you can't forget to turn it off when the job is done. That saves energy and money.