To set the humidistat on a humidifier, determine the proper relative humidity for the home and switch the dial to that setting. You need a humidifier, such as those mounted on furnaces or a standalone unit, and a relative humidity guide, such as those provided by humidifier parts sites or on your humidifier.
- Determine your home's relative humidity
Using the chart on your humidifier or provided by a humidifier parts store, locate the current outdoor temperature and its corresponding humidity setting on the chart. Some charts may differ, but typically indoor humidity is lowest in the winter. For example, an outdoor temperature of 40 degrees Fahrenheit leads to a recommended humidity setting of 45 percent.
- Locate your humidifier's humidistat controls
Determine where the controls are on your humidifier. If the humidifier is attached to your furnace, the controls are likely to be mounted on the face of the furnace with a dial near the humidity chart. Find the correct humidity setting and turn the dial to that setting.
- Adjust controls as necessary
Adjust the controls as necessary based on the environmental symptoms. Not all homes are the same, and tightly sealed ones do not require as much humidity. Mold or mildew growth means you need to turn the humidity down, while static electricity issues and dry mucous membranes means it needs to be turned up.