Q. I have good-quality thermal pane windows, but one of them has developed fog in between the glass panes. Is there any way to repair it?
A. There is no way to remove the fog from between the glass panes. The air gap is sealed at the factory with special desiccant (drying) chemical inside.
The entire double pane glass unit must be replaced.
Most good-quality thermal windows come with at least a 10-year warranty.
And they should last many years more than that.
If you can't locate the contractor who installed them, you will probably have to pay for the labor costs yourself.