Original posting:
I bought some NOS double glazed aluminum single hung sash for my own house. They were stored outside for some time and looked fine on carefull inspection when I bought them. Once installed in my finished home in December in PA, they started to fog up between the sheets.
40 years experience with some unconventional double glazing suggests that the fix might be to drill a couple of small holes in the sheltered top edge of the outer lites to vent the moisture.
Anybody ever try it? Thoughts?
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We have results! I drilled the outer lites on my steamed up insulated panels and they were dried out in hours.
Glass: insulated panels 35×28, aluminum spacer 5/16, plastic muntins sandwiched between to give the appearance of 6 lites, two panels in each single hung alum. Frame, four frames, total of eight panels.
Mfg date: 30 Mar 1996. Installed for the first time Dec 2003
Orientation: due south.
Outside temp: 35-60, humidity: 40-90 during the week
Two of the eight panels had ‘substantial’ condensation, by which I mean, visible droplets of a size and density that little streams were running down the glass.
I decided to drill a ¼” hole in each panel approximately 2″ from each of the upper corners. I tried a spade bit for “glass and ceramic” but even after sharpening it with a diamond hone got nowhere. At a home show I picked up a set of twenty ‘Dremel’ type bits that are coated with diamond powder for $5 and one of them lasted thru three of the four holes. A second bit did the forth hole. Using a battery powered drill it took 1 to 5 minutes per hole.
I put two holes in the first panel and when I checked seven hours later it was almost completely dried out. So I thought let’s try one hole in the second panel. Three days later it was about 40% dried out so I put a second hole in it and it dried out over night.
Going forward, I am going to plug the holes in one panel and leave the other open and see what happens.
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In the original thread Junkhound mentioned that he felt storm windows were probably better than double glazing. I have a room that has the above mentioned double glazing on one wall and a 55 yr old wood doublehung w/ storm on another wall. I have an infared thermometer and checked the inside surface temp of these windows 10 or 15 times at outside temps of 5 to 30 degrees F. I checked around 11 pm so that sun wasn’t a factor. To my surprise the wood w/storm showed a glass surface temp equal to the insulated panel or one to three degrees warmer. So in this case at least insulating value appears about the same. NOTE: This is not science, it is one observation that in itself proves nothing, but I hope others will make their own observations.
Replies
Very interesting. I'll try it. That will keep my low e coating and create something more like the old Pellas, with the vents. I did have one experience with them fogging, after a sloppy painter plugged the holes.
What are your summers like? Here in humid Va, I'd expect summer fogging from cool interior temps.
Nothing to lose, a little more information on those bits please? My panels are substantially larger. This'll be interesting.
PAHS Designer/Builder- Bury it!
The climate here in SE PA is in the same zone as most of VA. We do get very hi humidity in summer. I too have wondered whether that will result in condensation caused by central air and that is one reason why I'm plugging the holes in one lite.
The bits I used are called 'diamond burrs' and if you google that yop get lots of hits. Have a look at item 2385299826 on ebay. Though these burrs have 1/8" shanks to fit a Dremel I think that Dremel speed will heat up the glass and crack it. A battery powered drill kept the glass cool and I had no problems. Try a 3/16 cylindrical burr held at a 45 degree angle to the glass.
When you post results please email me if not in this thread.
Thank you. I'm headed to ebay. Most certainly I'll share results of my experimentation- that you started. No battery drill lives here, but I do have slow speed ones. My guess is the same as yours about a Dremel. I'll practice on an uninstalled pane. PAHS Designer/Builder- Bury it!
A problem with this approach is that double pane windows often have a coating of some sort on the inside, and once that's exposed to the air it begins to discolor. But it can't hurt to try.
Another way I've heard of doing it, vs drilling through the glass, is to drill through the edge of the sash and through the metal separator. Takes a keen eye, of course, to hit the separator and not the glass, and it won't work for the old Andersen glass-edged units.