Welcome To The
Dew Drop Inn!

This Winter, Help Your Customers Solve
Problems With Condensation Before They Start.

Along with cold and snow, winter brings condensation —the fog and frost that forms on windows and glass doors. It can cloud your view, freeze on the glass, drip on the floor, and generally cause trouble.  Because they are the first thing in from the window, blinds and shades often are incorrectly blamed as a source of the condensation.  Even though it's not the blinds, your customers may ask you about controlling the moisture that forms and freezes on their windows.  Here's what you need to know.

Where does Condensation come from?
First, it's not the blinds.  And it probably isn't the window, either, unless the window's seal has failed. Condensation forms when water vapor in the air it comes into contact with surfaces cooler than itself. It's pretty much the same thing on the inside of a window in December as it is on the outside of a can of root beer in August —both show condensation.  In a home, condensation occurs when there is excess humidity. While windows and doors are the first place you see the fog of condensation, other items in a home are affected by the excess moisture, too.  Walls, ceilings, wall coverings, pictures, furnishings, —even the blinds and shades can be adversely affected by high humidity.  All air contains a certain amount of humidity or moisture. Most homes, in areas of the country that get cold, have humidifiers that add moisture to the air in winter.  When your heater is on, the added moisture from a humidifier can keep you more comfortable.  But other everyday things can increase the humidity, too. Cooking a meal, taking a shower, washing clothes, even breathing all tend to increase the humidity.  In fact, the normal daily routine of a family of four can add as much as 18 gallons of water vapor a week into the air.

The more water vapor in the air, the higher the relative indoor humidity. Since outside air usually contains less water vapor, its circulation through a home tends to dilute the inside humidity most of the year. In the cold of winter, though, the normal flow of air in and out of a home tends to be restricted. Newer homes tend to be more tightly sealed and well-insulated, restricting air movement through the house. In older, less tightly sealed homes the air moves more quickly, reducing the relative humidity in the home.  Because of this, there is often less condensation in older homes.

So What Can Be Done To Ease Condensation?
The best way to eliminate condensation is at the source, so most often, eliminating condensation is as simple as turning down the humidistat.  Most humidifier manufacturers warn against setting the humidity to ideal relative humidity.  In general the most accepted setting ranges are:

OUTSIDE TEMPERATURE	INSIDE RELATIVE HUMIDITY*
-20º or lower (brrr!)	don't exceed 15%
-20º to -10º	don't exceed 20%
-10º  to  0º	don't exceed 25%
0º  to 10º	don't exceed 30%
10º  to  20º	don't exceed 35%
20º  to  40º	don't exceed 40%
* assuming 70º indoor temperature

After Humidistat settings, the next thing is air flow.  If you have condensation problems, you need to circulate more air.  Setting the heating system fan to "on" instead of "auto" will allow more air circulation and will distribute humidity more evenly throughout a house.  Ceiling fans at a low speed are also a great source of air flow.  Most fans are reversible for winter use to use at a low speed in a circulation mode. Kitchen and bathroom fans can also help.   Make sure that attic and crawl spaces are well ventilated, too. 

So there are a lot of things you can do to take an active role in educating your customer about controlling condensation —it's easier than holding your breath.