Repairing Your Furnace Humidifier

Posted on: 15 January 2015

Furnace humidifiers will sometimes stop working. When the humidifier isn't working, this either means that there is a clog or that the solenoid water valve has burned out.

Saving Money on Parts

When these parts are damaged, they usually need to be replaced. However, the cost of replacing a humidifier is often expensive, so it is a good idea to purchase a few replacement parts when you first get your furnace. The older the furnace, the more expensive the replacement parts are.

Preparing for the Repair Process

To begin the heating fix on the humidifier, you will need to first shut the power off to the humidifier. Then, you need to turn off the water valve and disconnect the old water line.

Testing the Solenoid Valve

The solenoid valve is an actuated valve that lets water travel to the humidifier. It is controlled by the thermostat. When the humidity reaches a certain point, the solenoid valve will then raise the humidity of the furnace.

To test if the solenoid is working, set the thermostat to a higher level so that it calls for heat. With the furnace running, attach one part of the multimeter to the wiring connection an attach the other part to the solenoid probe. Switch the humidistat to a very low temperature and the multimeter should not register a reading. Then, turn the humidistat to a very high level. If the multimeter shows 24 volts, this indicates that the solenoid is working properly. Otherwise, you will need to replace it.

Replacing the Humidifier

If you need to replace the entire humidifier, you will need to compare the opening to the amount of space that is needed for the new humidifier. In most cases, newer humidifiers are smaller and you will not need as much of an opening. You will therefore need an adjuster plate. You can attach it with sheet metal drilling screws.

Trace the opening onto the plate. Then, use the tracing to cut a new opening. When cutting the opening, make sure that you do not damage the AC coil. The humidifier can then be hooked onto the edge of the new opening. Tilt the top of the humidifier toward the duct. After you have leveled the unit, secure it with self-drilling sheet metal screws. Then, install the summer/winter damper and the bypass duct. Then, connect the water line to the solenoid valve and turn the power back on.  

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