Two Simple Ways To Stop Your Humidifier From Overflowing

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Two Simple Ways To Stop Your Humidifier From Overflowing

If you live in an area where the weather gets cold and dry this time of year, don’t forget to set your humidifier accordingly. Whether you have a portable humidifier or a furnace-mounted unit, having some moisture added to the air inside your home will help prevent dry, itchy skin and alleviate breathing problems.

However, if you haven’t used a furnace-mounted humidifier in a while, you might be alarmed to find water overflowing the unit onto the floor. There’s no need to panic; Repair Clinic has two simple ways to stop your humidifier from overflowing. While fixing an overflowing humidifier isn’t complicated, it’s a good idea to familiarize yourself with how a furnace-mounted humidifier works.

How does a furnace-mounted humidifier work?

As noted above, there are two different types of humidifiers: portable and furnace-mounted. A portable humidifier is a self-contained unit that will add moisture to the air of any individual room you set the appliance up in. A furnace-mounted humidifier will add moisture to the air of every room in the home via the home’s central air venting.

Furnace-mounted humidifiers have the potential to overflow

Since portable humidifiers require you to manually pour water into the unit’s reservoir yourself, there’s little likelihood of the unit overflowing. If a portable humidifier does overflow, it usually comes down to user error! Furnace-mounted humidifiers, on the other hand, automatically add water and, therefore, have a greater potential to overflow.

How water is supplied to a furnace-mounted humidifier

A furnace-mounted humidifier is attached to either the warm air duct or the return air duct and is powered by the furnace control board. Water is supplied to the unit through a water supply line which is commonly regulated by a saddle valve or another kind of manual shut-off valve. The humidifier operates while the furnace air circulation blower fan is running. As the blower fan runs, the furnace control board sends 120 volts of alternating current to the humidifier or to a transformer which steps the voltage down to 24 volts.

The home’s thermostat will normally have a setting that runs the furnace’s circulation blower fan only, so if the room air is a comfortable temperature, but still very dry, the furnace can operate the humidifier to add moisture to the air without heat.

A humidistat sends voltage to either a water inlet valve or a drum drive motor

Humidifiers are controlled by a humidistat which monitors the level of moisture in the home’s room air. To add moisture, the humidistat sends voltage to either a water inlet valve, if the humidifier is a “flow-through” style unit, or a drum drive motor, if the humidifier is a “reservoir” style unit.

Water flows continuously in “Flow-through” humidifiers

For “flow-through” humidifiers, the water inlet valve stays open and allows water to continuously flow into the humidifier when the blower fan is running, adding moisture to the room air. The water is distributed through a wick filter to assist in the evaporation process. Any water not evaporated will drain out the bottom of the unit to a floor drain or condensate pump.

A float triggers a valve to allow water to enter “Reservoir” style humidifiers

On “reservoir” style humidifiers, the water supply line connects to a float and valve assembly which maintains a specific water level in a reservoir pan. When the water level in the pan drops low enough, the float will trigger the valve to open and allow more water to enter the pan. A motor rotates a drum with a filter pad attached through the water in the pan which adds moisture to the air being circulated through the drum.

Furnace-mounted humidifiers require regular maintenance

Keeping your furnace-mounted humidifier working efficiently requires regular maintenance. This includes replacing the wick filter or the drum’s filter pad periodically. It’s also a good idea to clean the interior of the unit and/or the reservoir pan every few months or more often if the humidifier is in frequent use. If you live in an area with high humidity during the summer months and/or you’re using an air conditioner in the hot weather, you should keep the humidifier’s damper closed (if it has one) until the cold weather returns. If the damper is left open when the air conditioner is running, some of the return air will bypass the refrigeration coil and potentially freeze up the coil. For humidifiers that have a damper, the damper lever is usually marked “Summer” and “Winter”; the “Summer” position closes the damper whereas the “Winter” position opens it.

How to fix an overflowing humidifier

Now, without further ado, here are the two ways you can stop your furnace-mounted humidifier from overflowing:

  1. Clear or straighten the drain hose – The humidifier’s drain hose could be kinked or clogged, causing the water to back up and overflow the unit. You should first check to make sure the hose is not kinked between the humidifier and the drain source. A kinked drain hose will need to be straightened to allow the water to freely flow through it. If the hose does not appear kinked or bent you should detach the hose from the drain pan and inspect it for clogs. If the hose appears clogged, you can blow compressed air through the hose to clear the obstruction. Of course, if the obstruction cannot be cleared or the hose is damaged, you should definitely install a new drain hose to fix the problem.
  2. Clean out the drain pan – No issue with the drain hose? Then you should inspect the humidifier’s drain pan. The drain pan can become obstructed by the build-up of mineral deposits carried by the water which will quickly cause the pan to overflow. This can be more of a concern if your home is supplied with “hard water” which contains more minerals than “soft water”. Remove the drain pan, or detach the necessary panels or housing to access the pan, and use a small flat-head screwdriver to gently clear any deposits from the drain port. If the clog is not easy to clear or the pan is damaged you should replace the drain pan with a new one. If the issue keeps reoccurring, you may want to consider installing a water softener system if your area allows it.
Humidifier Overflowing? Humidifier Troubleshooting

DIY it with help from Repair Clinic

Repair Clinic believes you can take on most repairs yourself provided you have the right guidance. That’s why the “Videos & Articles” section of the Repair Clinic website has thousands of procedural videos, step-by-step guides, articles, and schematics to help you fix your heating and cooling system, home appliance, or outdoor power equipment. Looking for a video to show you how to replace a drain pan on a Model 45SH1 Skuttle Humidifier? Click here. Want to learn about the four different ways a humidifier can fail to get water? We’ve got that covered, too.

Use genuine OEM parts to fix your humidifier

When you need a new part to fix your humidifier, you want to make sure you’re using a genuine original equipment manufacturer (OEM) replacement part. Genuine OEM parts come direct from the humidifier’s manufacturer (Bemis, Bryant, Carrier, Goodman, Holmes, Honeywell, Skuttle, and York are just some of the companies Repair Clinic stocks parts from) so you’ll know that part is designed to work with your specific unit. Using generic parts is risky as they can interfere with proper humidifier operation resulting in premature failure. Just enter the full model number of the humidifier in the Repair Clinic website search bar to see a list of all compatible OEM parts. You can then use the “Part Category” navigation filter (example: “Drip Bowl & Drip Pan”) and “Part Title” filter (example: “Drip Pan”) to identify the exact part you want.

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