On 18 Apr, 07:35, Mike Lane wrote:
On Thu, 17 Apr 2008 20:52:04 +0100, Harry Bloomfield wrote
(in article ):

25 years old and no such problems here. The gap is not a vacuum, but
filled to a similar or slightly less pressure to normal atmosphere.
Were it a complete vacuum, then there would be about 14 pounds per
square inch of pressure on the glass - multiplied by the area of the
glass. The seals should not fail after 8 to 10 years, they have an
indefinite lifetime, but most companies seem to provide a 10 year
guarantee - then disappear. Check the terms of your guarantee.

Yes of course - I hadn't really thought about it properly. The panes would
never stand the pressure. (I should have remembered the 'collapsing can'
experiments that science teachers loved to demonstrate in the old days :-)).



I have heard of one DIY solution, if you are completely stuck. It
involves drilling holes in the seal between the panels in two opposite
corners and circulating warm dry air through for some days, before
re-sealing. From memory the method used silica gell in a sealed box,
with a fish tank pump to circulate the air via small pipes in a closed
loop through the box, pump and window. Then re-seal the holes with
silicon sealer as you withdraw the pipes with the idea to leave a
slight vacuum between the panes. It is supposed to be very effective
and the slight vacuum helps pull the seals in.

I don't think that would help. The misting is definitely not condensation -
it's more like the haze one gets on the inside of a car windscreen that's not
cleaned for a few months - not very obvious until it gets into direct
sunlight, when it looks horrible.

--
Mike Lane (UK North Yorkshire)
To contact me replace invalid with mike underscore lane

DG units nearly all fail sooner or later. 25 years is possible but
rare. 15 nearer the average. Nowt you can do about it except replace
them.

cheers
Jacob