How to Wire a Humidistat to a Thermostat – Simple Steps Parallel wiring, on the other hand, lets everything run independently air conditioner comes on to attain a set temperature regardless of the humidistat’s setting. Most modern ACs have an inbuilt circuit for humidistat control and all you have to do is plug in the humidistat wires at the right ports. How to Wire a Honeywell Humidistat | eHow 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.