Wiring a Humidifier to a Furnace Blower

A man works on a furnace.
What You'll Need
Screwdriver, Philips or slotted
Wire strippers
12 gauge braided wire
Wire nuts (optional)

Typically, a furnace blower’s function is to get rid of the moisture within the area to which it provides heat. Furnace blowers are equipped with hot metal tubes that make it possible for the moisture to get “flushed out.” When air circulates the area and goes right into the heat exchanger, its exposure to the hot metal tubes removes the moisture. In order to bring back moisture back inside the house or any given space, an automatic furnace humidifier should be installed.

Step 1 - Shut Off Electrical Power

Before doing anything to the furnace blower, electrical supply should be turned off. There are two ways to remove electrical power and that is to either switch off the power in the main circuit or pull off the safety switch that provides the main power for the furnace.

Step 2 - Take the Cover of the Electrical Control Box

The cover of the wiring should be removed. Using a screwdriver, remove the lid of the electrical control box. Aside from the wiring, the box also has the contactor or the circulation fan motor relay. The contractor or the motor relays is distinguishable through a tag attached to it. It is either located by the side or underneath the switching mechanism.

Step 3 - Prepare the Wiring Set Up

The motor control contractor should be attached to the electrical box. A 12-gauge wire can be used to make the attachment. This step is done on the mounted humidifier. In order to run the wire inside the electrical box, a knock hole should be removed. The screwdriver’s end can be used for the round metal plug removal.

Step 4 - Attach Wires to the Humidifier

The ends of the two wires used to connect the contractor and the electrical box should be stripped. These wires will transport the electrical power to the humidifier. The two wires have two separate functions. One wire will serve as the ground wire or the neutral wire for the humidifier at 120 VAC and one will serve as the power wire. A humidifier in a 220 VAC edition will end up using both of the wire as its power wire. Wire nuts should cover all the bare connections in the setup.

Step 5 - Wire End Stripping

The other ends of the wires running back to the contractor should be stripped. The neutral lug should be attached to the ground or neutral wire. The lugs are found within the furnace connections. A tag should be attached to the wires referring to it as “neutral or ground.” It can also be called the white wires set.

In the case of the blower motor, the lower part of the motor contractor should be attached to the black power wire.

The main point of the set up is to attach the humidifier to the wires in charge of feeding the circulation motor.

Step 6 - Complete Task

Put the cover back on and test the system.