Moisture inside a double-glazed window pane

Page 2 of 2  


But it won't force out moisture. Sure, a little might go out, but all you're effectively doing is evaporating the condensation _inside_ the thermopane. The water is still there, and will recondense again.
You need stronger measures to get the moisture out. Eg: drying agents like silica gel.
--
Chris Lewis, Una confibula non set est
It\'s not just anyone who gets a Starship Cruiser class named after them.
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Dunno, Chris, might not get it all out, but I'd think it would get a lot, if you got temp to a high enough but still safe level, kept it there long enough, and did it on a hot, dry day so ambient vapor pressure was low. Might need to open crack a little to help it along. No doubt replacing window is best option, if landlady will spring for it.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Making the assumption that there's an crack in the thermopane unit, in order to force 50% of the water out, you have to heat up the air enough to have the air volume double in size. That's pretty darn hot. If I remember my physical chemistry, with ideal gasses [1], we're talking about roughly doubling the temperature - relative to absolute zero. eg: in the neighborhood of 300C or 500F.
You're likely to fracture the glass or set the caulking and/or wood framing on fire. I'm sure that the seals wouldn't take that either.
Now if there isn't a crack (eg: moisture was by slow diffusion through imperfect seals), the thermopane is likely to rupture (explode) long before you get the air inside the thermopane to that temperature.
[At 300C/500F, a thermopane that was mostly sealed, but at STP, would have an outward force of roughly 15 pounds per square inch. On a 2'x3' window, that works out to be over 6 _tons_ on the glass. Like parking two hummers on it.]
Heating to displace moisture works well, but only when you have air circulation. A thermopane unit doesn't. By definition.
If you had _two_ holes, and blew warm, dry (however you got it dried) air through, that'd be different.

Indeed.
[1] For all intents and purposes, air at STP is close enough to an ideal gas that "rough" approximations work. If you want it to 6 figures, I'd have to crack out the books ;-)
--
Chris Lewis, Una confibula non set est
It\'s not just anyone who gets a Starship Cruiser class named after them.
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

We might drill 2 holes in the spacers between the panes and feed air through a tube into one hole while warming one pane with a hair dryer.
If the condensation has actually etched the panes, we might separate and polish them with a Continental greenhouse glass cleaning solution containing fluorine.
Nick
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

All of this makes sense if we're assuming the moisture is the condensate of moisture saturated air. I guess I'm assuming the opposite, that rain has been entering through a leak. Seems to me this would alter the calculations. In time, faster with heat, it should diffuse to equalise with ambient conditions. This could take time, depending on size of opening, or using two holes as you said.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Actually, I'm not assuming that. The assumption is that the seal has become somewhat defective, and the original dry air (or argon) inside the unit has become replaced with moist air.
Once moisture is inside the thermopane, it don't make no difference how it got there, nor whether it entered as a liquid, vapor or solid. It's air and vapor/liquid/solid water that equilibriates at a certain point given the amount of water and the temperature.

Assuming that the crack that let the moisture in is anything short of a honking big hole, simply evaporating the water and waiting for it to diffuse out will take a very long time. There's essentially no external circulation because the hole is too small. The only air going through the crack is that pushed out by thermal expansion of the air inside the thermopane.
Infinitely long if the ambient air outside is anywhere near as humid.
It may have taken years for the thermopane to fog up with daily temperature cycling and the existing crack. How many years do you expect to be heatgunning it? ;-)
The humidity inside the thermopane may well be lower than summer ambient conditions, but in winter, it's high enough to condense (or even freeze) out. In other words, trying a simple heat trick during a humid summer day may make the problem _worse_ (as the window cools off, it sucks in air with more moisture than is already inside the thermopane).
In order for this to even remotely work, you have to forcibly replace the air inside the thermopane (positive circulation, eg: two holes) with what probably has to be artificially dried air. An air compressor with a drier would probably work (but heaven help you if you forget/plug the exit hole!).
Or introduce something inside the thermopane that captures the water (eg: silica gel).
Then seal up the holes.
--
Chris Lewis, Una confibula non set est
It\'s not just anyone who gets a Starship Cruiser class named after them.
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Chris Lewis wrote:

I meant that it might not, in fact, be at equilibrium, but well above that due to rain getting in.

I did consider this- why I suggested opening crack/ hole and doing it in hot dry day. But come to think of it, cold dry day would be better- less moisture in air at same rh.

This would be a good last step. Maybe open up a diaper if you need a plentiful source :) If he removed window from frame, he could try dripping water out, then inject and drain out alcohol.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Related Threads

    HomeOwnersHub.com is a website for homeowners and building and maintenance pros. It is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.