• If you have a bypass humidifier, which redirects hot air through a water panel to create moisture in the air, locate the central humidistat or control button and turn it off, says Jeff Richard, general manager of Northern Colorado Air in Fort Collins, Colorado. The humidistat may be controlled by the thermostat or located next to it, or mounted to the ductwork near the humidifier, he says.
• If your unit has a damper, close it. Otherwise, even if it’s off, the humidifier will work against the air conditioner, which is designed to remove moisture from the air, Richard says.
• Turn the water supply to the humidifier off. Richard says you can usually find it by following an attached quarter-inch plastic or copper tube from the unit to the water heater.
• Wait until fall to replace the water panel, which is also called the filter, Jewell says. “When you confirm the heating system is working properly, you will be reminded to put in a new one,” he says.
With the water turned off, the existing panel will dry to prevent it from attracting mold, he says, because you’ve closed the damper and shut off the water supply. Richards says when replacing the water panel, use one recommended by the manufacturer to maximize the unit’s efficiency. You may be able to buy a water filter suitable for your unit at a home improvement store. Prices range from $10 to $25. If not, contact an HVAC professional.
Does your home have a whole-house humidifier? Tell us about your experiences in the comments below.
Editor's note: This is an updated version of an article originally published on May 5, 2014.