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I'm having all my windows replaced - professionally, so, not a DIY. This was prompted by the fact that on all of my smaller dual pane windows (~36x48), the outer glass (if it's glass) appears to be caved in, or bowed in, so much so that I have determined the outer sheet of glass is touching the inner sheet of glass. (Last winter I had 1/4" layer of ice on the inside in the middle of the window where the glass sheets touch.) Walking through my subdivision, I see dozens of windows with this same effect. Is there a dual pane strategy where the outer sheet of glass (or whatever) is intentionally formed not flat?
 

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I'm having all my windows replaced - professionally, so, not a DIY. This was prompted by the fact that on all of my smaller dual pane windows (~36x48), the outer glass (if it's glass) appears to be caved in, or bowed in, so much so that I have determined the outer sheet of glass is touching the inner sheet of glass. (Last winter I had 1/4" layer of ice on the inside in the middle of the window where the glass sheets touch.) Walking through my subdivision, I see dozens of windows with this same effect. Is there a dual pane strategy where the outer sheet of glass (or whatever) is intentionally formed not flat?
Check out that issue with a Goggle search and "high altitude installations".
Ron
 

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no,what is happening is the heavy argon/krypton gas has leaked out of the igu causing a partial ''vacuum'' causing the panes to bow,this usually occurs at lower night time temperatures

during the day the sun warms the glass somewhat raising the pressure between the panes which returns them to a more normal position
 

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Toms...I question your assessment of the issue. If gas leaked out, the inside glass would eventually fog. But I agree that heating from sunlight will affect what is between the glass panes, be it a vacuum or w/argon. My theory is: windows without argon, only have a vacuum drawn on the glass, sucking in the panes. Glass with argon have the gas introduced after pulling the vacuum, so the suction action on the glass is reduced.

The answer to the question is: it is not a problem if the glass bows is slightly.
 

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Bill i'm just speaking in very general terms [a scientist i ain't:no:]

i think the molecule size of the gas is much smaller than air which is why air does not replace the lost gas,no air no moisture no fogging

if the glass is bowing enough to touch i think it is a problem:wink:
 

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Discussion Starter #6 (Edited)
Gentlemen (I'm assuming), thank you for your comments.

More info: Altitude 5000ft
Temp: 81F
Time: 3pm MDT
Subdivision Construction: 1990-1995

Windows: 48h x 28w Dual pane air gap (est) 3/8" Windows are in shade.

#1: facing East
Deflection outer pane (center): concave 1/8"
Deflection outer pane (bottom): concave 1/16"
Deflection inner pane (center): concave 3/16"

#2: facing South
Deflection outer pane (center): concave 3/16"
Deflection outer pane (bottom): concave 1/16"
Deflection inner pane (center): concave 3/16"

Measurements taken from 24" horizontal straight edge centered between left and right pane edges. The visual cue that the panes are touching is a prismatic effect at the point of presumed contact (like an oily sheen on water). This effect is seen today to same degree as when the outside temperature was below zero and a 1/4" layer of ice had formed at the center of the inside pane. No fogging has occurred.

I found this from a search for "high altitude installation" (thank you for that): http://www.cardinalcorp.com/data/pdf/residential-brochure.pdf (page 43) which describes the effect, but does not explain it, merely how to build for it.

However, this report: http://www.fenzi-na.com/pdf_docs/Ka...mplodding%20-%20US%20Glass%20April%201999.pdf does describe the effect and the probable cause.

I am satisfied.

Thanks to all who joined in this conversation.
 

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collapsed

Tom is totally correct...

This same discussion pops up now and then in here - this is a reply that I did from one in jan 09: http://www.diychatroom.com/f17/condensation-ring-pella-window-36129/

What you are seeing is is a classic example of center-of-glass condensation due to "collapsed glass".

In a normal window the center-of-glass is the warmest part of the entire window system, but in the case of your windows there is a slight vacuum between the lites which is causing them to collapse inward resulting in the glass being closer together at the center (possibly even touching in some cases) and in less insulating value at that point.

This is typically a manufacturing defect and it is a warranty issue.

You need to contact your window distributor asap and explain the problem to them.

Same applies here; who built the windows and what is the date on the window logo (corner stamp)?
 

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one other thing,i think this problem may be a contributing factor with reflective heat damage on nearby vinyl sided homes,the concave glass in conjunction with Low e coatings may act like a parabolic mirror

not just your problem but also one for your neighbors
 

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one other thing,i think this problem may be a contributing factor with reflective heat damage on nearby vinyl sided homes,the concave glass in conjunction with Low e coatings may act like a parabolic mirror

not just your problem but also one for your neighbors

Yep.....
 
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