Moisture On Windows
Your humidistat is set too high if excessive moisture
collects on windows and other cold surfaces. Excess
humidity for a prolonged time can damage walls especially
when outdoor air temperatures are very low. Excess
moisture condenses on window glass because the glass is
cold. Other sources of excess moisture besides overuse of
a humidifier may be long showers, running water for other
uses, boiling or steaming in cooking, plants, and drying
clothes indoors. A tight, energy efficient house holds
more moisture inside; you may need to run a kitchen or
bath ventilating fan sometimes, or open a window briefly.
Storm windows and caulking around windows keep the
interior glass warmer and reduce condensation of moisture
there.
Humidifiers are not recommended for use in buildings
without proper vapor barriers because of potential damage
from moisture buildup. Consult a building contractor to
determine the adequacy of the vapor barrier in your
house. Use a humidity indicator to measure the relative
humidity in your house. The American Society of Heating
and Air Conditioning Engineers (ASHRAE) recommends these
maximum indoor humidity levels.
Outdoor Recommended Indoor
Temperature Relative Humidity
----------- ------------------
+20 F. 35%
+10 F. 30%
0 F. 25%
-10 F. 20%
-20 F. 15%