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Do Humidifiers Cause Mold?
The question should be, can humidifiers cause mold? The answer is yes, but only if they are not properly maintained. Mold in a humidifier is a much more common problem with portable units than it is with whole-house humidifiers.
Humidifiers are supposed to improve your indoor air quality (IAQ) in the winter or in dry climates by helping you achieve the ideal indoor humidity. But if you let mold grow, you’ve defeated the purpose. The trick is to never set the humidity level too high.
What should I set my humidifier to?
According to the Environmental Protection Agency (EPA), the ideal indoor humidity for health and prevention of mold growth is between 30% and 50%. You can start to feel uncomfortable at 55% humidity, and anything 60% or above is considered high humidity and conducive to mold growth.
Prevent mold in portable humidifiers
Set the humidity level between 30% and 50%. Follow the manufacturer’s instructions for how to properly set the humidity level. To prevent mold from forming in the filter, clean it regularly. Change the water in the water reservoir regularly, as directed. Clean the portable humidifier at least weekly, or as directed.
Prevent mold in whole-house humidifiers
Most whole-house humidifiers manufactured today, including Trane’s, are designed to prevent mold from the start, with features like controlled moisture distribution and automatic shutdown. They also connect to your home’s water supply, so water flows without you needing to refill a reservoir.
You can use your smart thermostat to set the desired humidity level between 30% and 50%. The humidifier will turn on when the indoor humidity level falls below your desired level. Once it reaches the appropriate level, the humidifier will automatically shut off.
Practice good maintenance
You can clean or change the humidifier pad (humidifier filter) annually or have an HVAC technician change it during an HVAC maintenance visit. Your smart thermostat may alert you when it’s time to change the humidifier pad.
Finally, depending on your climate, you may want to turn off the water supply to the whole-house humidifier in the summer. You just need to remember to turn it back on in the winter.
Learn more about whole-house humidifier maintenance.
Expert review by Sean Goddard, Product Manager, Coils & Indoor Air Quality