These humidistats provide accurate and reliable humidity control for indoor air quality systems, according to the manufacturer. A sensor in the HR-1 is made of human hair. When the relative humidity of the surrounding air increases, the length of the hair increases, and vice versa. The change in length is transferred to a micro-switch or slide-wire potentiometer.
Regin HVAC Products, 273 Canal St., Suite 222, Shelton, CT 06484; (800) 394-2739.