Double Glazed Sash

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johnleeke
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Double Glazed Sash

Postby johnleeke » Wed Dec 11, 2013 9:24 pm

The book, Details of Building Construction, is cool because it shows double-glazed sash and double-sashed windows were used way back in 1899.

Image
http://books.google.com/books?id=bIY5AQ ... 22&f=false
I've got two sash just like that from a school house in Minnesota built in the 1890s. They lasted over a century, so I wonder why the big modern window manufacturers don't make a double-glazed sash that lasts more than 10 or 20 years. I asked the guys from Marvin why at the window conference last spring and they had more than a dozen excuses.

Have you ever seen old double-glazed sash or double-sashed windows?
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DoubleGlazingHistory-DetailsofBCp34.PNG

johnleeke
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Re: Double Glazed Sash

Postby johnleeke » Wed Dec 11, 2013 10:52 pm

Scott Tripp and I had this related discussion over on Facebook:

Scott:
John re your post, I am guessing the early double glazing system you speak of used wood and putty not a insulated glass unit. With IGUs (Insulating Glass Units with two panes of glass sealed at the edges) most issues are with the seals on the IGU failing. The study I read by large German company made it appear that major causes of failure in IGU were contamination in manufacturing process and in service exposing seals to either moisture or UV light. My take away was that if carefully a designed and installed IGU (inserted in well-designed window) with the IGU made in a clean room environment could almost achieve an unlimited life span. It would be also be very expensive. The fault is not with the idea if IGU, it is just the current state of product development, rushing to lowest possible cost and quality. Many parts of the process currently all are kind of awful, poor design, cheap manufacturing, shoddy install. Both of window and its IGU.

John:
Scott, your take on this is Exactly my own take. NASA could make the perfect IGU. Marvin and the other manufacturers can only make the imperfect IGU.

Scott:
Not jusy Nasa. My sense is that the German company that authored the report (AFG maybe), seemed capable except for two things: they only had control of a portion of process and were at mercy of window manufacturing companies and installers. They make only the IGU and nobody, or few companies, wanted to pay the price for high quality IGU.

John:
Let me put it this way. In the 1940s the US Constitution was sealed into what we would now call an IGU, as the perfect way to preserve the Constitution. They took extra-ordinary measures to seal that sucker up, spending more than $600,000 doing it. (I consider that a NASA-scale effort.) The sealing system was way way more than any IGU that is made to day. It failed in 12 years. The fundamental concept is flawed. Plus, I have the exception that proves the rule. In the early 1960s a company here in the States made a welded-glass edge that does not fail at the edges. However, it does fail by baseball, as I personally learned in 1961. Of course, they no longer make it, because it is not a disposable product.

(this discussion was copied here from Facebook with permission from Scott)

johnleeke
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Posts: 144
Joined: Thu Aug 29, 2013 8:21 pm
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Re: Double Glazed Sash

Postby johnleeke » Sun Sep 10, 2017 2:18 pm

Build your own double pained sash with built in drying system:

Image

More info here:
http://www.de12ambachten.nl/eng-greente ... glass.html


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