Nick Hull wrote:
I have some double glass windows that are fogging up inside. Is there
any practical repair?


If you are really stuck for cash.......

You can do a hack job that will get you by for another year or two
simply by drilling two or three 3/16" diameter holes through the OUTER
glass pane just above the lower framing. You can buy carbide glass
drills cheaply.

The fogging will go away in a couple of days.

Not quite as good insulation as a new double pane unit with low thermal
conductivity gas in it, but pretty close.

That will turn your double pane window into the equivalent of a single
pane window with a "storm window" over it. Millions of homes used to get
by with those in the winter before they invented double glazing.

A drilled unit will get "scummy" on the interior after a couple of
years, and AFAIK there's nada you can do to fix that when it happens.

There's a service based in Canada which "repairs" fogged double glazed
windows by drilling them, flushing them out and snapping "dirt filters"
into the drilled holes so the windows can still breathe, but much of the
stuff which causes them to film up gets kept out. I don't think they've
got many US agents yet.

http://www.fogfree.ca/

Whatever you do, DON'T try and drill a tempered glass panel like those
found in patio doors unless you want to experience seeing a network of
cracks propogating up it for about one minute while making a crinkling
sound like something out of a horror movie. (DAMHIKT) G

Jeff

--
Jeffry Wisnia
(W1BSV + Brass Rat '57 EE)
The speed of light is 1.8*10^12 furlongs per fortnight.