Fog in New Windows

[Alan Whitehouse]

Hi,

I put in brand new low-e argon windows. The windows all face south and I live in a cold climate (Toronto).

Right now there are pathes of fog in most of the window. It seems to get worse when the sun hits and it is really cold. Unfortunately we have not had these over the spring and summer so I can't say if it will go away or not. It started with one window and then another and another and so forth. Once a window gets it, it has not gone away with changes in weather.

The window manufacture told me this was normal.

Can anyone confirm?

Alan

[Moisés Nacio]

"Alan Whitehouse" wrote

[trader4]

It depends on where the humidity is. If it's condensation between the panes, the windows are defective. If it's condensation on the inside, that can happen depending on how humid it is inside and how cold it is outside. Even with the best insulated windows, the inside surface can get cold enough to cause condensation. Do you have a humidifier and is it set too high?

[Goedjn]

Condensation *ON* the windows in normal and not a problem. Condensation *IN* the windows is a sign of seal-failure. You need to be very clear about which thing is happening. The "It has not gone away with changes in weather" implies that you can't wipe it off, right?

[m Ransley]

Is it inbetween glass panes not wipeable with a rag or inside the home on glass and can be wiped off.

[Joseph Meehan]

If it is in-between the glass then it is NOT normal. It is a defect and should be covered under warranty.

If it is on the glass, then it is a simple physics question. The glass is lower than the dew point. The dew point is not the same measurement as humidity, but they are related. The dew point does not change with temperature it is a measure of the total amount of water. The humidity is a measure of the amount of water divided by the total amount possible. The humidity is 100% when the current temperatures equals the dew point or less.

Now what to do. You can wipe it off, you can reduce the humidity inside the house, you can warm the windows.

When you have window treatments that cut off air circulation to the windows, it allows the window glass to be colder and when it get below the dew point you get dew on the windows. Curtains do not stop moisture nearly as well as they stop heat. Sometimes opening the drapes or curtains will take care of it. Of course adding an additional window pane will also help since it will cause the glass on the inside to be warmer.