Misting DG window and drilling glass: a result!

[Chris Hogg]

After about ten days, the misting has cleared completely. For the first few days, the inner surface of the outer pane was absolutely streaming, because water got in when the drill first broke through, from the water spray I was using to cool the drill bit. Otherwise the misting might have cleared a lot sooner. Fortunately, we've had nothing but warm dry sunny weather. Time will tell how it behaves through the cold wet winter months.

If I get more misty DG windows in the future, I will probably drill two holes, one each top and bottom, to encourage air circulation through the gap between the panes and speed up the de-misting, and then seal the top hole with a spot of glue when the misting has cleared to help preserve the insulating properties of the air gap, but leave the lower hole open to let the air gap breathe.

[Andrew]

Todays BBC1 Homes Under the Hammer (repeat of a 2011 prog) showed a house in Gainsborough where the bathroom window had four inches of water inside the 'sealed' DG unit. Can't understand how it didn't freeze up and break the glass.

[Lee]

Now you have the hole, wouldn't it be just as easy to squirt some desiccant in there and seal it back up, or am I missing something?

[JimK]

er well.... there's the reason why it steamed up in the first place that's still unresolved...

NB what dessicant were you considering "squirting" in there?

Jim K

[Dave Plowman (News)]

Not much point in having double glazing if air is free to circulate between the two?

[The Natural Philosopher]

absolute tosh

[Tim Watts]

Conc H2SO4?

Might do the spacer bars though...

[Jethro_uk]

Because as it froze, it had room to expand.

[JimK]

mmm "explosive gas filled" DG units anyone? ;>)))

Jim K

[Bob Minchin]

What sort of drill bit & diameter did you use in the end?

Bob

[Tim Watts]

That's OK - the H2 would displace the air through the OP's vent hole and the H2 would no longer be explosive :)

[Dave Plowman (News)]

So no point in using argon, etc, either?

[JimK]

Ah but wouldn't the DG units be *less* efficient as a result? ;>)

Jim K

[Chris Hogg]

Like this

but 3 mm.

From my earlier post:

[Lee]

It's not that difficult to get silica gel granules down a rubber tube. Depends on the size of the hole though, obviously :)

[The Natural Philosopher]

worse than a vaccuum innit? ;-)

what matters is not absolute seal, but how much movement there is, and the important movement is not in and out of the DG unit, but the circulation inside it, and one tiny hole makes piss all difference to that.

[Tim Streater]

As long as you don't have small holes in both panes. If you do, then a strong cold wind directly onto the window will slowly force cold air into the house.

[JimK]

/It's not that difficult to get silica gel granules down a rubber tube. Depends on the size of the hole though, obviously :) /q

And I'd expect how inventive you can be at spreading them out so as not to look completely like a (small) pile of entrapped spider shit.... ;^)

Jim K

[polygonum]

Do you have any figures as to how much air can be forced, by wind pressure alone, through a pair of, say, 3mm holes, especially if not aligned across the two panes?

Do you have any figures for how much air can be forced, by wind pressure alone, through the seals round the glass, between inner and outer frames, round hinges, between wall and frame, etc., in a fairly ordinary house?

Anticipating your answer, I'll say "Me neither", but I'd be surprised if the glass holes allowed anything like as much as the rest of the window/frame/wall.

[Tim Streater]

It's not going to matter too much if they're aligned or not. Wind pressure will force air into the gap between the panes, which will then be forced out into the room.

Really? When we moved here, there'd fairly recently been extension work. All the new windows were wooden double-glazed, so we thought, that's OK. Wrong. They were all extremely poorly sealed, and cold air came round the edges of all of them (the DG units themselves were OK).

So we had the whole lot replaced within six months. Result? One or two rooms are still getting cold [1] and I'm taking steps to fix that. But in the main, as the new windows have rubber seals and do not leak air, it's a major improvement.

[1] E.g. the kitchen. But I think there are holes to the outside in the outer wall, and cracks in the inner wall. So, strong wind and same result. That will get fixed when we redo the kitchen, as these issues are behind kitchen units.