When Good Humidifiers Go Bad

As a mold expert, I’ve walked into some pretty bad situations. It’s not unusual for people to be unfamiliar with all the inner workings of their homes, and many are surprised to learn that the utilities that help their house function can also be causing problems. At the top of this list of appliances that need to be monitored and maintained is the furnace humidifier.

What You Need to Know

During the cold and dry winter months, a furnace humidifier is a necessity, creating much-needed moisture in the house. But during that time—and even throughout the year—there are some things homeowners should know:

  • Humidity can cause mold. If the humidifier is set too high, the moisture will condense on the colder areas, such as windows and exterior walls, usually near joints where insulation is lacking. If you see water beading on your windows, your house is too humid. Turn down (or off) your humidifier until you find the right balance of moist and dry air.
  • Excess moisture also causes condensation on the humidifier parts. That combined with the calcium and dirt that accumulate on the filter make your humidifier an ideal breeding ground for mold.
  • Your furnace humidifier creates moist air that is then blown into the house through vents. Again, the combination of dirt and moisture provides an opportunity for mold to grow and thrive. This mold exists past the filter, though. No matter how great your filter is, it’s useless against mold in the ducts.

What You Can Do

Don’t let this information discourage you from using your humidifier, though. Used properly and carefully, it is a very useful tool. Here are some steps you can take to ensure you have the right amount of humidity for creating a comfortable and safe home:

  • Watch your windows: Use your humidifier’s control to turn the level down until you don’t see condensation on the edges of the windows.
  • Keep your humidifier and filter clean: Look for cleaners (usually available in a hardware store) that help dissolve the mineral deposits—and remove one of the components necessary for mold to grow.
  • Keep your ductwork clean: Look for a reputable, experienced company to perform this service. There are wonderfully qualified companies out there, but there are also a lot of hacks. Do your research, check reviews and ratings, and hire the right professional for the job.