Things You'll Need
A Honeywell humidistat controls a humidifier's run time. A humidistat can mount to a wall, like a thermostat, or in an air conditioner's return duct near the air filter. Typically, wall-mounted humidistats control a single room's humidity, and duct-mounted humdistat's control whole-house humidity. A transformer in the humidifier sends a low-voltage signal to the humidistat through a set of 18- to 22-gauge wires. When the humdistat detects a demand, when the relative humidity of the air reaches a set point, an internal switch closes and the completed low-voltage circuit turns on the humidifier.
Turn off the humidifier's power source. If the humidifier plugs into a receptacle, then unplug the humidifier. If the humidifier hard wires into the air-conditioning system or directly into the circuit breaker box, then turn off the appropriate circuit breaker, labeled "Humidifier," "Air handler" or "Furnace."
Strip 1/2 inch of the insulation from both wire strands in both low-voltage wire sets with wire strippers. Two two-strand low-voltage wire sets extend into the humidistat's base about 6 inches. Each wire set contains a black- and a white-colored wire strand.
Grab one humidistat lead and one black-colored low-voltage wire strand. Twist the ends together with pliers. Screw a wire nut over this pair of wires. The interchangeable humidistat leads, the two short pieces of wire extending from the rear of the humidistat, can connect to either black-colored low-voltage wire.
Twist the remaining humidistat lead to the remaining black-colored low-voltage wire with the pliers. Screw a wire nut over this pair.
Twist the two white-colored low-voltage wires together with the pliers. Secure them with a wire nut.