The humidistat uses human hair as the sensor medium. The hair stretches as the humidity increases and shrinks as the humidity decreases. These changes are
transmitted to a micro switch (two switches). The setpoint switch affects the position of the micro switches in relation to the hair element. The setpoint can be set at between 10% and 95% RH. As the contacts are of the changeover type the humidistat  can control both humidification and dehumidification. This tried and trusted construction with few movable parts gives a high degree of reliability and accuracy.

Typical applications
Can be used to controll a humidifier or a dehumidifier or for on/off controlling of a fan. Can also be used to alarm when the humidity exceeds or falls below a pre-set
level.