How To Fix A Leaky Humidifier

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As the weather outside gets colder, the air inside your home will get dryer, which can lead to chapped lips, skin irritation, and breathing difficulties. This is why residents who live in areas that experience cold, dry seasonal weather can really benefit from a well-maintained humidifier.

To add moisture to the air inside your home, a furnace-mounted humidifier requires a dependable supply of water coming into the unit. But what do you do if that water is leaking out of the humidifier? Repair Clinic has five likely causes you should investigate to assist you in fixing your leaky humidifier. Since the first step to successfully troubleshoot an equipment problem is understanding how that equipment works, let’s start there…

Understanding how a furnace-mounted humidifier works

There are two different types of humidifiers: portable units that can add moisture to the air in individual rooms and furnace-mounted humidifiers that can add moisture to the air being sent through the central air ducts to every room in the home. This article will address furnace-mounted humidifiers.

A furnace-mounted humidifier is powered by the furnace control board

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 at a comfortable temperature, but still very dry, the furnace can operate the humidifier to add moisture to the air without heat.

A humidistat monitors the level of moisture in the air

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.

“Flow-through” humidifiers distribute the water through a wick filter

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.

“Reservoir” style humidifiers use a drum and filter pad

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 periodic maintenance to work efficiently

Keeping your furnace-mounted humidifier working efficiently requires regular maintenance. This includes replacing the wick filter or the drum 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.

5 reasons why your furnace-mounted humidifier is leaking water

There are five likely reasons why your furnace-mounted humidifier is leaking water. Here are the things you should look out for and tips for how to fix the problem:

  1. Clogged drain hose  – If the humidifier’s drain hose is kinked or clogged, the incoming water can back up and begin leaking out of the unit. You should first check to make sure the hose is not kinked between the humidifier and the drain source. Next, 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.
  2. Obstructed drain pan – The humidifier’s drain pan can become obstructed by the build-up of mineral deposits carried by the water. This problem can be exacerbated if your home is supplied with “hard water”. You should remove the drain pan or detach the necessary panels or housing to access the pan, then use a small flat-head screwdriver to gently clear any deposits from the drain port. If necessary, you can replace the obstructed drain pan with a new one to resolve the issue.
  3. Clogged water evaporator pad – Over time, the water evaporator pad (AKA “wick filter”) can become clogged with calcium and other deposits which can cause the incoming water to ride along the top of the pad and drip down outside the water collection tray. Installing a new pad should fix the problem. You can avoid this problem in the future by replacing the evaporator pad, or wick filter, regularly as part of a maintenance routine.
  4. Damaged water distribution tray – The water distribution tray rests on top of the evaporator pad and is designed to direct the water to drip evenly into the pad. If the tray is damaged, clogged, or misaligned, water may be leaking outside the humidifier. The first step is to confirm the tray is in good condition and is seated properly on the wick filter. If you notice any cracks or chips, replace the old tray with a new one.
  5. Cracked water line – It’s also possible that one of the water lines has cracked. You should inspect the lines for damage and check for a loose or corroded fitting at the water inlet valve. If you spot any damage or corrosion, install a replacement water line.

Fix your humidifier with genuine manufacturer parts

If you need to replace your humidifier’s wick filter, drum pad, drain pan, water distribution tray, or any other component, Repair Clinic recommends using only genuine manufacturer parts to ensure your humidifier can operate effectively for years to come. That’s why we stock genuine OEM parts direct from such manufacturers as Bemis, Bryant, Carrier, Goodman, Holmes, Honeywell, Skuttle, and York. To find the right part that works with your humidifier, enter the full model number of the unit in Repair’s “Search Parts Online & Get Answers” search bar. The resulting list will show all of the parts compatible with your humidifier. You can then use the “Part Category” and “Part Title” navigation filters to refine that list to identify the specific part you need.

Repair Clinic provides free repair resources for do-it-yourselfers

Want to learn the correct way to install a new water inlet valve on a Skuttle Model 2000 Humidifier? Or get some maintenance tips to get keep your humidifier in peak condition? Repair Clinic provides free repair resources through the “Videos & Articles” section of its website. Do a little exploring and you’ll find thousands of “how-to” videos, step-by-step guides, articles, and schematics covering all major home appliances, heating and cooling products, and lawn and garden equipment. Whether you’re a professional technician or a do-it-yourselfer, Repair Clinic wants to be your repair partner!

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