User Guide
EVERYDAY
OPERATION
• What should my humidity setpoint be? The outdoor air temperature affects how much humidity can be
retained by the air in your home. Use this table as a starting point. Then adjust the humidity control to your own
comfort or until condensation appears on the windows.
• What is a frost setting? Some humidity controls (such as Prestige, VisionPRO IAQ, and HumidiPRO) contain
a Window Frost Protection feature which limits humidity output based on outdoor conditions. For example, on
colder days, the air in your home can hold less humidity. The humidity control automatically lowers the humidity
setpoint accordingly, to prevent frost from appearing on the inside of your windows.
Lower the frost setting by one value each morning that you see frost or condensation on windows. Allow 24
hours for the new setting to take effect before re-adjusting. Once you have this set to a comfortable level
without condensation, you will not need to adjust further. You can adjust your humidity setpoint without
worrying about condensation.
Manual humidity controls do not have built-in frost settings. They require you to adjust the humidity setpoint
when the outdoor temperature changes. Use higher humidity setpoints when the temperature is warmer, and
lower setpoints when the temperature is cooler.
Outdoor Recommended Relative
Temperature Humidity Setting
-20°F (-29°C) 15%
-10°F (-23°C) 20%
0°F (-18°C) 25%
10°F (-12°C) 30%
20°F (-7°C) 35%
>20°F (-1°C) 35%
MCR2798
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Steam Humidication System 69-2286EF—05
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