Is Something Wrong with Your Whole House Humidifier?

You’re probably here because you’re trying to find out what’s wrong with your whole house humidifier, or you could just be researching whole house humidifiers as a possible solution to humidify your home. Whole house humidifiers, also referred to as furnace-mounted or duct humidifiers, are great ways to increase the moisture in your home. They generally take less maintenance than console tabletop humidifiers, but they can still have occasional problems starting up or not humidifying your home as well as it did when it was new. Despite these potential problems though, maintaining proper humidity in your home is a great way to protect your health.

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Parts of Your Humidifiers

Before going into the different problems that can come up, it’s good to go over a brief overview of how whole house humidifiers work. Despite the different types of humidifiers, they all work to do one thing: increase the moisture in your home. In order to do that, they need a water source, a method for turning that water into vapor, and a way to know when you need more moisture. All of these functions come to the following basic parts:

Water line – This is the main water source for your humidifier. Your humidifier gets water from a main water supply that leads to your humidifier, often through a saddle valve. This then leads to a solenoid valve that delivers water to your evaporation unit. The water supply system is a great place to start if you’re experiencing any leaks or problems with your humidifier running dry.

Humidifier Solenoid
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Solenoid valve – The solenoid valve controls the inflow of water to your humidifier. It’s controlled by electric current to shut the valve open or close. Attached to the water delivery system, whole house humidifiers will also have filters to help slow calcium and mineral buildup. And like the water supply, the solenoid valve can also be related to leaks or problems with your humidifier not delivering any water. Since the solenoid valve does run on electric current, a dead solenoid valve could mean something is wrong with your humidistat or power delivered to the solenoid.

Evaporator – Depending on the type of humidifier you have, the evaporator can work in any number of ways. Since liquid water needs to be evaporated into water vapor to increase the moisture in the air, your humidifier needs a way to easily change liquid water into water vapor. This is where the different types of humidifiers come into play, which we’ll get into in the next section. Each type can run into its own set of problems. During your research, watch out for different terms that refer to the same type of humidifier.

Humidistat – To make sure that you get the humidity you need, the humidistat works to detect the humidity in your rooms and let the humidifier know when it needs to turn on. This switches on the water and any fan or furnace that will help evaporate the water delivered to the humidifier. Problems with your humidistat can be a little trickier to diagnose, but with a multimeter and some familiarity with electrical diagrams, you can usually find out what’s exactly wrong with your humidistat.

Types of Humidifiers

Drum Humidifier
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Reservoir (Drum) humidifiers – These humidifiers’ have a rotating evaporator pad that works to increase the moisture in the air that passes through. The pad rotates into a reservoir of water to bring it up into the passing air to increase the humidity in the air that passes through. You’ll find that drum-style humidifiers also come in types that include its own self-powered fan or not. The advantage of having its own fan is that the humidifier doesn’t need to passively rely on the air coming from your air circulation system to drive the humidity up.

Drip style humidifiers
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Flow-through (Drip-style) humidifiers – Flow-through humidifiers work on the same basic idea as reservoir humidifier, but there’s no reservoir to keep the water. Instead, the water is passed directly into an evaporator pad that is positioned in the stream of air that passes through. Flow-through humidifiers will generally use more water because it produces a lot more extra water that drips off of the evaporator pad, which is why they’re also called drip-style humidifiers. The most common problem you might face with the humidifying mechanism on flow-through humidifiers is that the evaporator components start getting clogged from mineral buildup.

Steam humidifiers – A steam humidifier boils water to directly send water vapor into your circulation system. They’re often the most effective way to humidify your home because it doesn’t rely on evaporation to increase the moisture. The use of boiling and hot steam means you have to make sure you’re using your steam humidifier according to manufacturer instructions. Not following the guidelines for use can damage both your humidifier and home.

List of Possible Problems

  • Water is Leaking – The first thing you need to do is figure out where the leak is coming from. Is the leak coming from before or after the humidification mechanism? Leaks in the drain mechanism are less common because the drain system is more simple, but it never hurts to be sure. Chances are, however, the leak is coming from somewhere between the main water supply to where the water is delivered through the solenoid valve. Every valve is a potential failure point for water to leak. Over time, parts can wear down from buildup or mechanical failure. You can try shutting the water off at various points along the water supply system to see if you can stop the leak at any point.
  • Humidifier is Not Turning On – If the humidifier is not turning on, there are a few places you can look, but they all come back to your humidistat. The signal from your thermostat to your humidistat could not be working, the power supply to the humidistat could be faulty, or something could even be wrong inside your humidistat if it’s not detecting the humidity correctly. If you’re comfortable with electrical diagrams and testing circuits with a multimeter, you usually pinpoint the problem. Check for any loose wiring. One person also found out his humidifier stopped working when he upgraded his thermostat, which changed the wiring setup.
  • No Signs of Water or Humidity – One of the most common problems with any humidifier is that the lines can be blocked from calcium and mineral buildup. Water passes through a lot of small lines, filters, valves, and evaporators that make it easy for them to become blocked. Check to see where the water could possibly be being blocked. Another check is to listen for the click of your solenoid turning on. Since a solenoid problem could be more than just the solenoid, I’ve given this problem it’s own point.
  • Buzzing Noises – Buzzing noises are going to come from any moving or mechanical part in your humidifier. Any rotating drive mechanism or fan motor could wear out from overuse or poor lubrication.

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  • Solenoid is Not Switching On – Your solenoid is fail to click on for two main reasons. The solenoid valve itself is broken, or it’s not getting the right signal from your humidifier. Check to see what signal your solenoid valve needs to open and if it’s receiving the correct voltage. If it is receiving the correct signal but still fails to open, then your solenoid valve is the problem. If, however, you’re not getting the right signal to the solenoid to begin with, you’ll have to investigate the humidistat and power delivery. For more information, The Spruce has a detailed writeup on how to replace a solenoid.
  • Funny Smells from the Humidifier – Funny smells are going to mainly be a problem with reservoir style humidifiers because of the standing water. Humidifier reservoirs need to be cleaned and disinfected regularly to prevent bacteria and mold growth. Follow manufacturer instructions for disassembling and cleaning your humidifier.

What You Can Do

Before you get started on any work for your humidifier, check to see if it’s still under warranty. Some manufacturers have policies saying your warranty will be invalid if you do any troubleshooting or work on the humidifier yourself. But if you don’t have to worry about voiding your warranty, feel free to diagnose the problem yourself.

Always be sure to follow safety recommendations from the manufacturer and follow general safety guidelines around water and power. If you are taking apart your humidifier for cleaning, maintenance, or repair, turn off the water supply and power to your humidifier.

Calling a professional is an easy way to get your humidifier fixed quickly, but you can save a lot of money and learn a lot by doing it yourself. Being able to repair your humidifier will depend a lot on how easily you can find the parts you need.

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