How to Install a Wall Humidistat

Let the open humidistat sit outside of its package for 24 hours so the humidity controls can adjust to indoor levels. Raise the thermostat until the system blower activates, then lower the thermostat to test the sensor's shut off function. Turn the thermostat to the recommended setting after the testing operation.

Place the humidistat on a flat and clean surface of an inside wall prior to drilling. Choose an area on the wall that is not exposed to heat or sunlight. Install plastic or foil vapor barriers for additional protection against moisture and condensation.

Drill a three-eighth-inch hole into the areas on the humidistat’s mounting plate that will hold screws of the same size. Place the mounting plate horizontally onto the wall, approximately 4 to 5 feet above the floor. Mark and drill another three-eighth-inch hole into the wall.

Run wires from the wall to the humidistat terminal. Pull approximately 6 inches of wire through the wall’s hole. Guide the wire through the hole drilled into the humidistat’s mounting plate. Stuff the hole in the wall with insulation material to minimize drafts during operation.

Attach and secure the mounting plate to the wall using 1-inch screws. The screw heads must be no more than one-fifth of an inch above the mounting plate.

Run the wall cables to the humidistat terminal’s connector screws. Those screws are usually on the back of the terminal.

Attach the humidistat cover plate using the three-eighth-inch screws. Push any additional wires back into the wall before securing the cover plate.