A humidistat is a device on humidifiers that regulates the amount of relative humidity inside a home or building. Controlling indoor humidity levels can make the air feel cooler or warmer, thus making the air more comfortable. Because there is less natural humidity in the air during the cold winter months, the humidistat settings must be altered. There are some basic guidelines to follow when setting a humidistat, but much of it comes down to personal preference.
Set the humidistat knob on the humidifier to the following winter settings as recommended by the Ask the Builder website. If the outdoor temperature is near -10 F, set the humidistat to 20 percent. If the temperature is near 0 F, set the humidistat to 25 percent. If the outdoor temperature is near 10 F, set the humidistat to 30 percent. If the outdoor temperature is near 20 F, set the humidistat to 35 percent. If the outdoor temperature is near 30 F, set the humidistat to 40 percent.
Examine the inside of windows to see if condensation or frost is developing. If these are present, the humidity is too high. Turn the humidistat down 5 percent and wait two to three hours to see if it solves the problem. If the problem persists, continue turning the humidistat down 5 percentage points at a time until there is no frost or condensation.
Examine areas of wood such as hardwood floors or window casings for signs of board separation. If the boards start to separate slightly, then the humidity level is too low. Raise the humidistat setting 5 percent.