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Humidity-Sensing Control Device

This device continuously monitors and controls relative humidity by connecting to high efficiency fans, humidifying or dehumidifying equipment.

The solid state humidity sensor is an electronic, temperature compensated sensor that is linear between 30% and 90% relative humidity with a nominal tolerance of 5%. The device includes a manual override switch that turns on a fan for an internally preset time (12 minutes) before restoring the system to automatic operation. The control also includes a Fan On light, indicating the operation of the controlled device. The internal SPDT (single pole, double-throw) switch allows the control of either humidifying or dehumidifying devices for the constant operation of a ventilation system, or a motorized cover or fan.

The manufacturer offers a fixed set point (FS) model, an adjustable (AS) versions, a remote sensing model (R) and a differential humidistat (D). The FS version has fixed summer and winter settings (35% and 55% relative humidity). The AS version is adjustable from 10% to 90% relative humidity. The remote sensing model R can control humidity up to 200' away with a remote lead (regular phone wire) . The differential humidistat (D), senses humidity remotely and at the control. If the remotely sensed relative humidity exceeds the relative humidity at the control, the system will not turn on on humidity rise. This device is used when multi zone humidity control is neccessary.

Environmental Performance

Humidity control can improve indoor environmental quality by managing moisture that can lead to mold and deterioration.

Quality and Durability

By controlling interior humidity, a home can be more comfortable for its occupants.


Unless controlled by relays, the maximum load for fans, dehumidifiers or motors can not exceed 1.8 amps. The recommended operating temperatures are between +5° to +45° C (41° F to 113° F).

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For accurate humidity sensing, the 4 3/4" x 3" x 1" (HxDxW) control device is surface mounted and installs on a single ganged work box. Remote sensors can be placed outside, must be protected from direct weather exposure however.

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Continuously monitoring relative indoor air humidity not only can maintain the desired comfort level for habitants or plants, it also helps improve indoor air quality by lowering the risk of fungus, mold or meldew and cuts heating and/or cooling costs all year long.

Base prices are FS: $79.00; AS: $89.00; R: $98.00; D: $125.00.

Disclaimer: The information on the system, product or material presented herein is provided for informational purposes only. The technical descriptions, details, requirements, and limitations expressed do not constitute an endorsement, approval, or acceptance of the subject matter by the NAHB Research Center. There are no warranties, either expressed or implied, regarding the accuracy or completeness of this information. Full reproduction, without modification, is permissible.