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"Defogging" double-pane windows .... a gimmick??

593K views 133 replies 57 participants last post by  Nathan 
#1 ·
I posted on another home forum about removing the condensation between the panes in my two 51" x 61" picture windows. I bought the house in December when there wasn't much condensation, but now it's pretty bad. The people who responded to post noted that I'd have to have the glass replaced entirely. That's looking to be around $700 - $800. But I saw a Yellow Pages add that advertised a company that could defog windows. So I started reading about it on the internet (which always requires scrutiny and skepticism) and there are a number of companies saying that, in many situations, windows can be defogged.

Here are a few:

http://www.defogit.com/
http://www.defogusa.com/HowItWorks.html
http://www.wcofa.com/
http://www.ccwwi.com/Default.html

Here's an article in the Ottawa newspaper about it:
http://www.ccwwi.com/images/Ottawa_Citizen_Article.pdf

Is this defogging process truly possible? effective? Anybody tried it?

BTW, the person who used to own this house is no longer living and I can't find out who installed the windows. AFGD is stamped inside the window and I talked to the local dealer of this glass manufacturing company. They said I'd have to find the contractor who installed the windows to initiate any warranty that may be valid on the windows .... basically a dead end for me.

Hoping for an inexpensive solution, but trying to be realistic....

Alex Z
Knoxville, TN
 
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#5 ·
Yes! Window defogging does work, and well.

First of all, you do not need a new window if just the insulated glass unit is foggy. There is MUCH more to be said! You can make the repair by replacing the insulated glass unit alone and retain the sash and frame assembly, or you can use the defog repair method you mentioned.

Second, moisture inside a window does not mean the seal has broken. A seal *may* have broken or it may not. The secondary seal of an insulated glass unit is not impervious to air. This is one reason why most every insulated glass unit has a moisture control product inside- a dessicant to absorb the inevitable moisture that will enter every ig during its lifespan. Often the moisture is present because the insulated glass has reached its moisture threshold; there is more moisture inside the glass than the dessicant can effectively absorb and hide.

Take an ice cube and place it on the "clear" window glass of similar age and design for between :45-1 min. You just lowered the dew point at that spot. Now wipe away the moisture from the outside of the glass. You'll probably find that there is also a moisture spot inbetween the glass too that you cannot wipe away. WoW! Your "clear" window has moisture in it! Where is the seal broken though? Hmmm?

Third, when properly defogged using the methods of the companies you listed in your question, the moist air has been replaced with a still, dry air space and the insulation ability of the window has been greatly improved from the wet condition and will insulate very near its newly manufactured state.

I've got six repaired windows in my own home and will continue to use this defog repair method to maintain my insulated glass as the rest of them fail. It has worked great!

If you do not have a company in your area to make this repair, then the intermediate cost option would be to have a glass company replace the insulating glass in your window. Buying a whole new window is an option, but may not be necessary unless you are unhappy with the window style or function.

'hope this helps.
 
#6 ·
How long defogged?

Hi jgiedt,

You mentioned you have six windows in your home that were defogged?

How long have they held up so far?

I have a similar problem in my house with some large (and large $$ replace, uuggh...) windows.

Thanks.

Mike R
Granite Bay, CA (sacramento)
 
#7 ·
I did them in phases, as they fogged. The first three or four has been 3 years. The others are a year or so. No problems. They look great. Simple science on gas in enclosed containers plus the fact that dry air insulates. Why would they all of a sudden NOT hold up? I like it!

Hi jgiedt,

You mentioned you have six windows in your home that were defogged?

How long have they held up so far?

I have a similar problem in my house with some large (and large $$ replace, uuggh...) windows.

Thanks.

Mike R
Granite Bay, CA (sacramento)
 
#8 ·
fixing windows

Condensation between the lites in an IGU is a cosmetic issue. Unless there is argon loss or there is corrosion of the LowE coating, there is no difference in energy performance between an insulating glass unit with condensation and one without condensation between the lites.

There is a common misconception that all dual panes are gas filled with something other than air – and technically air is a gas of course - when in fact less than half of dual pane windows manufactured today have an argon (or other) gas infill between the lites.

There is very little likelihood that an older dual pane window ever had a gas infill because until the past few years very few dual pane IGU's were filled with argon. And many of those that were filled probably lost the argon fill years ago due to migration thru the (mostly obsolete) materials that were used to seal the unit at that time.

Gas escaping from the interior of the IGU does not cause fogging. Fogging is almost always (with a few rare exceptions) caused by moisture penetrating the seal between the two glass panes.

If anyone is interested, I can make this very long and technical, but for a quick answer, repairing a “failed” IGU is never a DIY project.

There are a number of companies out there that are advertising that they can clear up foggy IGU’s. In some cases they can give the appearance of “fixing” the IGU in the right circumstances.

The condensation between the lites is almost always caused by an excess of moisture that has entered the space because of a blown seal. The IGU “repair” does not take into account the seal failure and does nothing for it. The IGU repair (or “fog-out”) folks simply arrange for the IGU to evacuate the excess moisture by drilling holes in the glass and placing a one-way valve that works with natural heating and cooling cycles to replace the air within the IGU airspace. Basically, air comes in thru the breach in the seal and goes out thru the one-way valve.

Again, I can get much more technical on how and why this works – although the “fog-out” guys (and if “fog-out” happens to be a trademark or use name of a particular company I am not aware of it – if so, then I am using it generically and mean no comment for or against a particular company or product) have all sorts of interesting claims on their various sites – often exaggerated and a few that are simply incorrect – concerning the performance of a typical IG window system.

Still, the basic concept is sound – with certain restrictions it may be possible to clear up the condensation between the lites of an IGU using the method that they promote. Again, they don’t do anything particularly earth-shattering other than allow air movement between the lites which allows the moist air to escape from between the panes – much the same as a single pane acts with a storm window.
 
#9 ·
" You need new windows."

Thought this was a DIY board with real tips, am a retired engineer, not one of those guys that sat behind a desk, have a complete metal, wood, and electronics shop and like to do everything myself. For one thing, a means to beat the credit card companies and the IRS, if some guy is charging you 70 bucks an hour for something you can do yourself, you actually end up paying over twice the price as you are using post tax dollars, and if you have to pay interest, just another slap in your pocket book. I built my own home in 1970 while carrying on a full time job, with good buying and hard work, had it paid off in three years. Also do all my own vehicle work, but do have my Ram reflashed now at the dealer, not about to pay $7,500.00 for the equipment required just for a particular brand of vehicle. Think this reflashing is crazy.

Another thing that is crazy is argon filled windows, I had to sell my own built home because of a job change and purchased my present home in 1985, it's paid off, been for, for some time, take good care of it, but also sharing your problems with foggy windows, I have six out of 45 panes that are foggy, was only four last year, two more this year.

Saving 60 t0 70% off the cost of new windows doesn't sound very good to me to have some guy come out to my home and make a mess out of it. Drilling a couple of holes is no big deal, I have the tools to get those holes to within +/- 0.0001" if I have to but they refuse to sell me those check valves. Then they claim to use a proprietary cleaning solution, what? Soap and water? Maybe even denatured alcohol, I have both air compressors, shop vacuums, and even a good sized vacuum pump and can experiment if need be. They talk about silica jel, I don't see that stuff in my windows.

And I don't throw away my dirty dishes either.

I feel like I was ripped off, not only by Koebe & Koebe that has no solutions, you are out of warranty, twenty years ago, they would sell direct to me, now it's strictly going to some lumber company that doesn't even have a parts book. They tell me to bring a window in and leave it there for a couple of weeks until the no-nothing rep comes around, how stupid do people think I and the rest of us are? And then to have to pay a huge markup on that stuff.

We are sure getting ripped off by these tax credits and DOE regulations, I checked into the R value of argon filled windows as opposed to solid insulated double thickness glass, the difference was infinitestmal. Maybe a guy would save a couple of bucks a year in fuel cost, but after the warranty would have to pay thousands and thousands of dollars for window replacements. And real insulated glass is neither recommended nor eligilible for a tax credit. Something is very fishy here, of course, real insulated glass won't leak.

Then there is the building inspector to deal with, believe the main requirement to get these jobs besides being a brother-in-law to the mayor is to have an IQ less than 1.998. Ran into this about replacing the hot water heater, wanted to install one of these new high effeciency forced ventilated heaters. First I can't install one in the basement because the snow may getter higher than the PVC vents, but why to you permit forced ventilated furnaces in the basement? Duh!!! And why can't I raise these cheap pipes a couple of feet? Besides with my overhangs, no snow every gets near the house anyway. You just can't do that. But after finding about all the problems with these heaters, extra electrical, failure of the control mechanism, but to top everything else off including one a one year warranty on the Chinese made electronic garbage, they only save 20 therms per year at an initial installation cost of several hundreds more.

Where is the savings in either these water heaters or argon filled windows? It's stupid and downright criminal to the home owner, and what about the guy with a 30 year mortgage and every increasing property taxes and interest rates? Work your can off just to end up with a pile of junk?

There has to be a way where a guy can clean and reclaim these windows, after 23 years, they still look new, except for that stupid fog in between the glasses. If I find anything, and I am looking, will let you know, already thought about painting them black.
 
#12 ·
" You need new windows."

We are sure getting ripped off by these tax credits and DOE regulations, I checked into the R value of argon filled windows as opposed to solid insulated double thickness glass, the difference was infinitestmal. Maybe a guy would save a couple of bucks a year in fuel cost, but after the warranty would have to pay thousands and thousands of dollars for window replacements. And real insulated glass is neither recommended nor eligilible for a tax credit. Something is very fishy here, of course, real insulated glass won't leak.
A 100% argon fill increases the thermal performance of an IG unit by 16%. A 50% argon fill increases the thermal perfomance of an IG unit by 8%.
It's a straight linear relationship.

Argon fill has nothing to do with moisture between the lites of an IG unit, windows with no argon can and do have seal failures.

If I may ask, what is solid insulated double thickness glass or real insulated glass?
 
#10 ·
Greetings!

I live next door to a IGU manufacturer. He's going to get a big question from me today! My first thought is to change just the IGU. I see folks going into the shop and buying new units everyday. Expensive? not supposed to be. You can easily change the unit yourself with just a few hand tools. Check the phone book or Internet and find a glass distributer like PPG. Don't go down to the local glass shop or window company!

-- pete
 
#13 ·
a friend of mine had one of these franchised services come to his house and do some windows. this was in spring of last year, by christmas time they fogged up worse than before.

he would have been better off just covering the glass with $50 bills, still wouldn't be able to see out, but the view would have been much better
 
#14 ·
just had the guy here...

just had the guy here associated with http://www.ccwwi.com.

first off, if its diy then i suggest you do so... kinda a rip off at $300 to do two skylights!

using a dremel type tool the guy put holes on the inside corners of the window (dependent of the size and ability to clean) then he sprayed some cleaning solution in and then a rinse. spray it in the top and suck it out the bottom.

"the installation of the 'micro' DefoggerTM valve and seal"
then he covered the wholes with clear plastic stickers! and the "valve" is another one of these stickers with grating holes... which will definitely keep larger insects out!

now, if this actually works then i will be happy but wish i paid less of course. i should have asked the guy how long it would take him before i agreed cause $300/hour is definitely a rip off!

i think given what everyone has said then i suspect whether this approach works or not is complex. for example, is the seal busted, how much of a leak does one have and is the leak allowing air from inside in or from outside.

i suspect it may be worth a try instead of replacement. if you diy and it fails then you are just out the time taken.
 
#15 ·
I checked with a local glass supply company, if I bring my casements in, he will measure them order the glass, and on the second two mile trip will install them for an average price of 100 bucks a window using new argon filled gas.

He will do that while I am waiting so I don't have to worry about rain if I pick a clear day. Windows are easy to snap out. Sounds like a much better deal than having some guy come over and drill holes.

I told him I have Koebe & Koebe windows, was to the factory and was told the frames were encased in epoxy. He said he has done many windows like that before and can replace the glass in about twenty minutes. Have no idea what his trick is, but willing to risk 100 bucks and find out, if okay, will bring the others in. I know he was in business for over 30 years.

Was questioning this

Paul Lacey
Chief Development Officer
Crystal Clear Window Works USA, LLP
475 Craighead Street
Nashville, TN 37204
Tel: 615-385-0240 ext 102
Fax: 615-385-0304
www.getthefogout.com

Never got a quote from them, can't do it myself, but looks like it could be a waste of both time and money.

Has anyone found replacement argon filled glass on the web? Koebe tells me they buy it but wouldn't tell me where. I tried a search, found plenty of new windows for sale, but never just that double glass with the aluminum frame.
 
#16 ·
Seems like I am up the creek again, have the old style Kolbe & Kolbe windows with the solid wood inside and a snap in vinyl strip on the outside that cannot be removed without wrecking it. A Kolbe rep came over, said these windows are not argon filled, just e-glass, and when that vinyl shrinks moisture can get it. And that is why I have moisture between the glass. Said I should seal those cracks where that vinyl has shrunk to protect the good windows, they will last a lot longer, better do that.

He let me in on a secret, http://www.cardinalcorp.com/ is a key supplier to all the major window manufacturers and their plant is only 50 miles from me. I feel the only way I can save my old windows, if replacement glass doesn't cost me an arm and a leg, is to route out the inside of windows and use a matching window molding that I can easily make while sealing the outside. Otherwise can buy new panels with the glass already installed for about 200 bucks a piece, that can add up in a hurry.

Terrible how this country of ours as become, while natural gas is strictly a domestic product in the last four years the price here went up from 64 cents a therm to $1.56, it's criminal as natural gas has nothing to do with OPEC, man, are we getting screwed.
 
#17 ·
I just thought I would toss this in - The Handyguys did a how-to podcast/blog post on replacing an IGU in a modern window. We didn't cover every possible window type but hopefully provide enough information for a DIYer to be able to do this themselves. We also covered how to glaze old windows.
 
#18 ·
Thinking about looking at real estate built in the 30's, hey it's 80 years later and some of these old homes still look great yet. These new story book homes with a two story high bunch of windows as wide as the front wall facing south are sure going to give someone problems down the road, and well before that last payment is made. One neighbor in a new story book home with a huge curve glass argon filled window had the outer glass pop up in our sub zero weather, he got a new window under warranty, but that does not cover installation. The windows I got stuck with, hey they were the greatest thing in the world are removed from the outside with that now unavailable vinyl strip that was told was epoxied in with no way to remove it.

Went to a couple building supply stores and looked at new windows, many of them you have to remove the entire frame to remove the panel to change a piece of glass, what happens if a kid throws a baseball at that? You're screwed, what are they thinking? But it is that way everywhere, if the motor and heater element goes bad in a dryer, it's cheaper to buy a new dryer than the price of those two parts. But then you are also stuck with a 30 buck recycling bill to carry your old dryer to the dump, they won't even pick it up!

I don't like the way our world is going.
 
#19 ·
foggy windows

I have read much but no real answers. First I will have to look up desiccant in the dictionary, then convert to the every day word.
Not sure what happened to my large Thermal window slider but I have 10 more just like it and some very large Thermal windows, basically every window in the house is the same (Andersen) and no help from them at all.
My windows are 3 years out of warranty and yet the company states the seal they use is 50 to 100 year flexible, guess not!
So some say seal break some say not seal problem, these windows were not cheap at installation and the manufactures are not offering any help or solutions for the window problems they have been aware of for 30 years.
My question is why haven't the thermal window manufactures come up with a home kit to resolve this 300,000,000 window problem in 2 countries??? There must be some serious money to be made in these window home kits at $50.00 bucks a pop. After all the manufactures make plenty of dough replacing broken windows from storms and from new contruction. So lets get some lobbyist going to Washinton and force the Companies to give something back to the suckers that fell for the pitch, maybe offer a vent repair kit with every window sold like it or not!
 
#20 ·
Broken seals are more cosmetic than energy losers.

Look at the R-values or U-values of the different window panes.

1. A leaking seal is not as good a good seal, but it may look O.K.

2. A good seal will rovide a clear view and and percentage improvement in insulation.

3. An Argon fill cavity will offer a bigger improvement over a unfilled normal glazing.

All are just small degrees degrees of insulation and none of them are very good compared to the rest of the walls (R2 compared to R19). In many cases, curtains or blinds drawn at night will offer more savings annually that fancy glazing.

It is very difficult to cost-justify the replacement of IGU panels. If you have a fogged window that is unattractive, that is a different story. The window insulating game is just that, when you consider that you probably lose more from infiltration around outlets in exterior walls than the benefit of up-selling glazing systems.

I replaced an oversized IGU panel in an old sliding door that was sound and had low infiltration because it was visually not acceptable. I was glad to pay the installed price for the panel. I have three other panels that are leaking, but it is difficult to find (depends on the time of day and the sun angle), so there is little reason to do so. My annual heat with R13 2x4 construction in Minnesota is very low (max of $85.00 for heat and hot water in the winter in Minnesota) for a 150 sf townhouse. Due to my north and east exposure, my AC is only a max of $50.00/mo over the average for lights, so sun is not an issue. In the winter, all windows coverings are obviously open during the day and most are closed at night. - I have a hard time justifying replacing a good looking panel or four on energy savings compared to what I normally spend.

Dick
 
#21 ·
fogged up

Good point what does Holiday Inn do for fogged windows?
I guess the point of my venting this situation, our income like many others has gone sour. Gasoline, food and the utilities companies has a death grip on our throats and can't afford to replace anything. I can only work part time at 60 and hubby at 65 will never be able to work again and nothing to show for it.
My neighbor said if I ever find a solution he will be happy to defog my window along with many other seniors in this community.
Rust is starting to show at the bottom between the glass of that Vinyl door window by Andersen.
 
#22 ·
What's the solution sprayed inside the window (see: http://www.cvwei.com/video.html)

What's the solution sprayed inside the window (see video: http://www.cvwei.com/video.html)?
Alcohol? Methyl Hydrate?
I have many fogged windows (34 panes in 19 windows).
So, I decided to experiment on one small fogged window (with two about 18" x 18" panes).
I drilled a tiny hole (pin-hole size) with a diamond bit and Dremel in a small window (interior-side, upper-left and lower-right).
Waited a few days.
The fog was still there.
Drilled another tiny hole in the exterior-side (upper-right).
Waited a few hours.
Still no change.

So, I took the other pane apart.
There are tiny desiccant beads in the hollow aluminum border between the two panes of glass.
If you shake or turn the the window, you may be able to hear them rattling inside the frame.
What's up with that? Well, it turns out that window manufacturers put desiccant beads in the window to absorb moisture.
However, that desiccant has a limited effectiveness.
Also, few windows are truly air-tight (hence, the reason for the desiccant beads).
Therefore, most (if not all) two-pane windows have a built-in obsolesence.
Imagine that?
That's nice if your business is selling windws, eh?

Therefore, since the window is still fogged, I'm wondering if the solution injected in the window has some evaporation and desiccant qualities?
It would be nice to know how to do this since $45 per pane (for 34 panes) would run about $1530, and replacing the 19 windows would be triple that cost (or much more depending on the quality of the replacement windows).

And replacment windows might fog-up too within a few years (if not sooner; especially for cheaper brands).

Hmmmmmm . . . so, I guess the next step will be to try and wash and drain the test window pane with alcohol.
And there's still one other unknown: the seals on the holes. Whatever is used should be semi-transparent, allow air to escape when air pressure increases, and keep insects out.
 
#23 ·
Made the holes in the upper-left and lower-right side of the windows a little larger (about 1/8 inch diameter), and the fog and water drops disappeared completely in both panes in two days (and there was quite a bit in both windows).
So, it appears that the holes can not be too small.
Next, I ordered some small one-way valves (which come on degassing coffee bags), and will (next) attach one to the top of each window, and place an air-permeable gauze over the lower holes of each window, and wait to see if the fog returns.
I believe the top valve must be a one-way valve (out), while the lower hole must have a simple two-way gauze (preferrably a transparent gauze to be less noticeable). If this works, it will be much less expensive than replacing all windows 17 windows in the house.
 
#24 ·
That's pretty cool. Assuming these holes were on the inside. I would be curious if you just used some clear tape and covered the holes how it would do. Or, if you could just leave them as is. The tape could easily be removed to defog as needed, if needed at all. Put the tape on when the humidity is very low and maybe you would be fine. Put it on when humidity is high then things may fog again.
 
#28 ·
The only question is what is the energy efficiency of the window now that you have holes in them?
How does it work if you have triple panes with the sheet of plastic up the center?
Good question.

With a 3 pane window, it may be necessary to do the same thing on the outside of the window. I've seen some of the service franchises doing their (e.g. Window Medics, defogit.com, etc.) process on both the inside OR outside. For a 3 pane window with fog on both sides of the center pane, it may be necessary to do the same thing on both the inside AND outside.

First of all, most windows only have an R-value of 2-to-4.
Expensive windows are only slightly better.
Compare those R-Values to that of a brick wall of about R-12.

______________________________________________________________
Table 1. Clear-Wall and Whole-Wall R-Values for Tested Wall Systems
#, System Description, Clear Wall R-Value (Rcw), Whole Wall R-Value (Rww), (Rww/Rcw) x 100%
1. 12-in two-core insulating units concrete 120lb/ft3, EPS inserts 1 7/8-in thick, grout fillings 24 in o.c., R=3.7, 3.6, 97%
2. 12-in two-core insulating units wood concrete 40lb/ft3, EPS inserts 1 7/8-in thick, grout fillings 24 in o.c., R=9.4, 8.6, 92%
3. 12-in cut-web insulating units concrete 120lb/ft3, EPS inserts 2 1/2 in thick, grout fillings 16 in o.c., R=4.7, 4.1, 88%
4. 12-in cut-web insulating units wood concrete 40lb/ft3, EPS inserts 2 1/2 in thick, grout fillings 16 in o.c., R=10.7, 9.2, 86%
5. 12-in multicore insulating units polystyrene beads concrete 30lb/ft3, EPS inserts in all cores, R=19.2, 14.7, 77%
6. EPS block forms poured in place with concrete, block walls 1 7/8 in thick, R=15.2, 15.7, 103%
7. 2 x 4 wood stud wall 16 in o.c., R-11 batts, 1/2-in plywood exterior, 1/2-in gypsum board interior, R=10.6, 9.6, 91%
8. 2 x 4 wood stud wall 24 in o.c., R-11 batts, 1/2-in plywood exterior, 1/2-in gypsum board interior, R=10.8, 9.9, 91%
9. 2 x 6 wood stud wall 24 in o.c., R-19 batts, 1/2-in plywood exterior, 1/2-in gypsum board interior, R=16.4, 13.7, 84%
10. Larsen truss walls 2 x 4 wood stud wall 16 in o.c., R-11 batts + 8-in-thick Larsen trusses insulated by 8-in-thick batts, 1/2-in plywood exterior, 1/2-in gypsum board interior, R=40.4, 38.5, 95%
11. Stressed-skin panel wall, 6-in-thick foam core + 1/2-in oriented strand board (OSB) boards, 1/2-in plywood exterior, 1/2-in gypsum board interior, R=24.7, 21.6, 88%
12. 4-in metal stud wall 24 in o.c., R-11 batts, 1/2-in plywood exterior + 1-in EPS sheathing + 1/2-in wood siding, 1/2-in gypsum board interior. NAHB Energy Conservation House Details, R=14.8, 10.9, 74%
13. 3 1/2-in metal stud wall 16 in o.c., R-11 batts, 1/2-in plywood exterior + 1/2-in wood siding, 1/2-in gypsum board interior, R=7.4, 6.1, 83%
14. 3 1/2-in metal stud wall 16 in o.c., R-11 batts, 1/2-in plywood exterior + 1/2-in EPS sheathing + 1/2-in wood siding, 1/2-in gypsum board interior. AISI Manual details, R=9.9, 8.0, 81%
15. 3 1/2-in metal stud wall 16 in o.c., R-11 batts, 1/2-in plywood exterior + 1-in EPS sheathing + 1/2-in wood siding, 1/2-in gypsum board interior. AISI Manual details, R=11.8, 9.5, 81%
16. 3 1/2-in metal stud wall 24 in o.c., R-11 batts, 1/2-in plywood exterior + 1/2-in wood siding, 1/2-in gypsum board interior. AISI Manual details, R=9.4, 7.1, 75%
17. 3 1/2-in metal stud wall 24 in o.c., R-11 batts, 1/2-in plywood exterior + 1/2-in EPS sheathing + 1/2-in wood siding, 1/2-in gypsum board interior. AISI Manual details, R=11.8, 8.9, 76%
18. 3 1/2-in metal stud wall 24 in o.c., R-11 batts, 1/2-in plywood exterior + 1-in EPS sheathing + 1/2-in wood siding, 1/2-in gypsum board interior. AISI Manual details, R=13.3, 10.2, 77%
______________________________________________________________

Windows with fog and water drops inside (moisture) have a slightyly reduced R-Value (than the same window with a dry airspace).
The holes are small (about 1/8 inch), and a one-way valve at the top, and a two-way valve at the bottom should restrict significant air-flow, but allow moisture to escape at the top of the window.

The R-Value (insulating quality) of the dry window (even with two small 1/8" holes (in upper-left and lower-right) covered with the one-way and two-way valves) may have a better (or equal) R-Value of a window full of fog and water drops.

The fact is, the R-Value of a fogged window is not too terribly less than an unfogged window (of the same quality).

The real problem is more of a cosmetic nature, and repairing the windows is preferrable to the cost of replacing 17 windows (with 34 separate window panes) if the R-Value of the window has not been significantly altered by the two holes.

I'll know in a few days if the one-way valves work. I also plan to try a simple bead of clear silicone caulk at the top hole, with a few pin holes in the caulk. That may be enough to allow moisture to escape, while being much less conspicuous than a small one-way valve (which came from a degassing coffee bag; see below).

 
#29 ·
Given that you have a bunch of windows you have a perfect opportunity to measure results with different methods.

I do not know how to measure r-value so I think thats off the table. My gut is that a 1/8" hole in one pane of a double pane window is statistically insignificant.

So we need to measure defogging and how well windows stay defogged.

1 window - do nothing to cover holes
1 window - tape over holes
1 window - your valves
1 window - caulk with pinholes
1 window - caulk only
1 window - caulk one hole only

you get the idea - Report back if any windows fogged up again and if any draft is noticed for holes not covered.
 
#30 · (Edited)
That's a good plan.

However, any strategy should include something covering the hole, even if it is gas-permeable, in order to keep insects from getting inside (between) the window panes.

It will take a few weeks to try all of the combinations, but I'll let ya'll know what happens, since I have 17 windows to work with.

Worst case, the windows have to be replaced anyway, so there's not much reason to not try to fix the existing fogged-up windows.

Here's another issue: tempered versus non-tempered glass. Drilling into tempered glass will shatter it. It's hard to tell what is tempered or non-tempered glass. So I tried using a camera flash to see if there was any difference. The first photo below is a non-tempered window (one I've already drilled). The second is a shower-door that I know is tempered glass, but there are no markings on it to identify it as being tempered glass. Notice the strange pattern on the tempered glass? But I'm not sure that is a definitive determination. Does anyone know of an easy way (aside from a $350 to $500 tempered glass detector) of detecting tempered glass?

Thanks!

NON-TEMPERED GLASS:


TEMPERED GLASS:
 
#31 ·
I recently spec'd Pella window for a job in NM and they all had small aluminum vent tubes to equalize the pressure inside the units during transportation from the manufacturing plant to the job site. The tubes are supposed to be trimmed off by the installer, but It seems like there is a big opportunity for mistakes if the installer is not up to speed. The thermal units were supposed to be "sealed" but perhaps that doesn't mean what the average person on the street would think sealed means.
 
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