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Fogged windows

levassep | Posted in General Discussion on May 26, 2015 01:14am

Hi,

How does the technique of drilling small holes in glass windows to removed fog and install valves that permits the evacuation of future humidity does compare with installing new glass in windows?

Does this technique gives an equivalent R-factor  of scelled glass?

Does this technique make sense from the energy converation point of view?

If the cost of this tecnique is half the price of putting new glass would you use it?

Here is a website where the technique is described : http://www.solutionthermo.com/en/services/ 

Thanks for your help,

Pierre

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  1. DanH | May 26, 2015 01:51pm | #1

    It can work, after a fashion, if the glass is of the right type and it's done properly.  And if you live in a climate where it makes sense.  You can also, of course, shatter the glass.

    "Valves" are not really necessary, just something (a plug of cotton, say) to keep bugs out.

    The R-factor of the glass should be (mostly) unaffected. 

    1. levassep | May 26, 2015 04:42pm | #2

      I'm in Canada north-east in a region where very low temperature are common in winter, minus 30 celcius (- 22 F) are common

      Also, if this process does not affect much the isolation factor of the window why in the first place put argon or other gaz in windows?

      1. DanH | May 26, 2015 06:15pm | #3

        Most of the insulation value of double-pane glass is due to having the thin layer of gas between the two glass layers.  Argon works somewhat better as the gas involved, but plain old air is nearly as good.  And by the time that the window has fogged most of the argon has leaked out already.

        One downside I didn't mention is that if the windows also have a "low-E" coating on the inside, that coating may turn from clear to a sort of metalic color, as moisture gets to it.  (Sometimes this may be hard to distinguish from plain old "fogging".)  Of course, the reason for drilling the window is because there's moisture in it, so drilling will not cause this problem -- it just won't alleviate it.

        Non-coastal Canada is an ideal location for the drilling technique, since the outside air, in the cooler months, is reasonably dry.

        The theory behind drilling is that you open up a slight leak to the (dry) outside air.  As the air in the window expands and contracts from temperature changes, any moist air in the window is exchanged with dry outside air.  The rate of air exchange is (assuming a SMALL hole) not enough to affect the insulating nature of the glass, but is enough to overwhelm the slower (moist) air leakage from inside the house.

  2. junkhound | May 27, 2015 12:55am | #4

    Cost of drilling hole is only 2 minutes of your time--

    are you saying there are charlatans out there that actually Charge big $$ for drilling a 1mm hole? I would NEVER pay for a 'service' like that!

    from the link:  "assess the condition"  == 95% of the time, all new windows I'd betcha!  Charlatans!

    Having taken apart a number of 'fogged' windows, unless very early in the event of 'fog' the glass is actually ETCHED by an enzyme reaction, not cost effective to try to dis-assemble and polish it out.

    OTOH, drilling the hole does let the window outgass and the etch will be less apparent without any actual moisture condensation.  Have done a few like that until I get around to replacing the glass  (I get my glass free off craigslist from folks replacing single pane windows, (the dummies) )

     Installed 'sealed' double pane windows in 1972 in own house, was screwed i admit, every one on the south side has leaked and etched.  Of course, folks say the process is much better now than it was in '72; check again about 2045 to see how well today's process has held up, the 100th aniversary of D-day

    I've used a heat gun and box cutter to remove the entire glass assy from the frame, then remover the seal strip from the etched glass, agian with heat gun and box cutter, then with butyl rubber seal new pieces of glass and re-install.

    Except for proscribed IRC requirement (mfg screw the HO via codes again!), I'd only use storm windows and single pane on new construction for my own house now. 

  3. DanH | May 27, 2015 07:35am | #5

    It should be noted that some double-pane glass made prior to about 1980 is apt to have fused edges rather than the separator strip with panes glued on both sides.  Fused edge glass is less apt to fail, but if it does you can't employ a technique which drills  through the separator -- you must drill the glass itself.

    1. edwardh1 | May 27, 2015 04:40pm | #6

      has there ever been an article on which windows are the most "fog up proof"? 

      its seems like an ignored part of building design.

      what causes fogging/seal failure?

      hurricanes?

      sunlight? being in a moving patio door? etc etc

      1. DanH | May 27, 2015 06:48pm | #7

        I've never seen such an article, but I don't follow the building trades press much.

        Some brands have been well-known to fog, others not so much.  But it changes as new technologies are used.

        The old fused-edge glass would rarely fail unless damaged (a shock at the wrong place in the frame would break the little sealed-off tube on one corner).  But fused edges were more expensive and did not work with "low-E" coating.

        The schemes with glass glued to a frame (basically all modern windows) are subject to seal failure.  And solar heating appears to be a factor in many seal failures.  I believe that some window makers attempt to have some sort of valve or expansion chamber to better handle solar heating, but these have their own failure modes.

        We have a house built in 1976, with all Andersen windows.  There are:

        1 sliding patio door, presumably glued-to-frame

        6 double-sash windows in the bedrooms (12 sashes), with fused edges

        2 single-sash windows in bedrooms with simple "storm window" construction

        2 double-sash windows in the living room (4 sashes), with fused edges

        2 double-sash windows in the family room (4 sashes), with fused edges

        1 double-sash window each in upstairs bath, kitchen, and utility room (6 sashes), with fused edges

        I count 26 fused-edge sashes total. 

        Two sashes (bathroom and living room) failed due to mechanical damage (eg, snowblower throwing a chunk of ice through the window).  Only the two upper (fixed) sashes in the family room failed for no apparent reason (and they just got bad a couple of years ago).  So 2 sashes out of 26 in 39 years.

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