I have seen this topic posted several times with no reply. I'm hoping someone has a solution. We recently bought a house with many large double-paned windows which are fogged between the panes. Is there anyway other than replacement to fix the problem?

The solution depends on a couple of things. 1.) is the fog a result of trapped moisture? 2.)what are your skill levels? If the fog is moisture only, they can be purged with dry nitrogen and salvaged. To purge you will need to drill a small (approx 1/8") hole in the top and the bottom in order to penetrate the space between the glass. These holes will need to be drilled vertically from the top and bottom. If you try to drill horizontally into the top and bottom you will probably hit the glass. Then you need a small bottle of nitrogen (available at any welding supply house) with a regulator so the pressure can be reduced to 1 or 2 pounds. insert an appropriately sized (slightly smaller than the hole drilled) piece of tubing in the bottom hole. Turn on the nitrogen to a pressure that is equivalent to what you could blow through a straw (be carefull or the glass could be blown out). Allow this to purge like this for two or three minutes. Wait about ten minutes for the nitrogen to absorb any extra moisture that remains, then purge again for an additional 2 or 3 minutes. If the window looks clear seal the top hole with a small amount of 100% silicone. If not, repeat the proceedure. Then remove the tubing and seal the bottom hole. This should give you an additional few years of use. And you can always repeat the proceedure at a later date when needed. When drilling the holes: Drill the bottom hole first. This will allow the the drill shavings to fall out rather than into the cavity. Then hook-up the nitrogen (before drilling)so as to blow the material out of the top hole . GOOD LUCK