How to Wire a Humidistat to a Thermostat

A humidistat helps to control a humidifier’s run time. It can be mounted on the wall like an air conditioner’s return duct or thermostat. Usually, duct-mounted humidistat controls your house humidity while wall-mounted humidistat controls just a single room.

Most humidistats are designed with a transformer that transmits low voltage signals across 18 to 22 gauge wire. When a humidistat detects a demand, especially when the humidity of the air reaches a particular point, the internal switch closes and the low-voltage circuit switches on the humidifier.

Connecting a humidistat isn’t a straightforward process as there are different humidistat thermostat combinations.

Humidistat Series vs Parallel Wiring

Humidistats can be wired in two ways: Series or parallel. The type of wiring determines how the two control the air conditioning and humidifier to achieve the desired humidity levels.

Series wiring requires the thermostat and humidistat to meet specific conditions before triggering the AC equipment. This means that if the humidistat is in the set range and the thermostat temperature is below range the AC and humidifier won’t kick in.

Parallel wiring, on the other hand, lets everything run independently. The 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. However, it is always advisable that you call in an expert to avoid creating conflict between the humidistat and the thermostat.

Wiring the Humidistat

This guide will explore how to hook up humidistat to a thermostat. It’s also however important that you seek professional help if you experience any difficulties.

• First, turn off the humidifier power source if it is plugged into a receptacle before unplugging the humidifier. If it is hard wired directly into the circuit breaker or the air conditioning system, turn off the right circuit breaker. They are usually labeled “Furnace,” “Air Handler” or “Humidifier.”
• Strip about half an inch of the insulation wire from both strands but in low voltage wire sets. Take two pairs of the low voltage wire sets and extend into the base just 6 inches. Each of the wires will feature a white and black colored wire strand.
• Grab one low voltage wire strand and one humidistat lead and twist them together using pliers. You can screw a nut over these sets of wires. The two short remaining pieces can either be connected to the white or black colored low-voltage wires.

This Humidistat wiring guide should help you find it easy to make the most out of your wiring experience. A simpler alternative would be to buy a thermostat with a built-in humidistat.