The windows were installed last September so first winter. When the sun hits the window the ice above the sealed unit melts causing water to run down the exterior of the glass.
The humidity in the house is normal with high efficiency furnace. Two of five windows do this. One west and one east.
Is this a problem with the sash seal on vinyl windows generally or just these two windows?
I have never seen this before. Sounds like it could be a defect in those windows. I would be contacting the supplier and get their thoughts on it.
It could be a result of two things:
1. On those two windows there is a small gap between the glazing stop and the glass.
In this case you have to remove the two side and bottom glazing stops and apply some silicon between the glass and the sash and close it back.
*The second option is that you have no air flow in front of the window and This is why the standing air get colder and create some water and ice on the bottom of the cold glass.
You should check the air vents in front of those windows to make sure its blowing air.
If you got the windows last September they should absolutely still be under warranty. If installed by the company you purchased them from you should let them know. There could also be a defect with the windows you purchased. No matter you want to get this looked at as soon as possible.
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