Even I have heard of this. They normally put it down to stresses in the fixing or the assembly of the unit. You then only need a tiny flaw and stress and temperature tend to make it fail.
Brian
As a conservatory roof, it is presumably toughened glass. It has long been known that toughened glass can spontaneously shatter. Causes can be slight damage during assembly; stresses due to how it is installed; nickel inclusions from manufacture, among others.
SteveW
She's replying to a 2014 post Brian - situation normal for H.O.H.
replying to Dave Chapman, Theresa Farley wrote: I was hanging out the washing on the line today heard a loud boom and the outside class on one of the panels has exploded luckily the glass has stayed put but the company is saying its not included in the gauretee just the building I will fight this today when I have the guy here to look at it
The original question was posted 13 years ago but in this case it's either a faulty DG panel or it's much more serious and the house and window frame is moving.
Yes this query comes up with amazing regularity. I wonder if the panels are under some stress and eventually the glass simply gives up and fractures. I wonder how long one can assume a double glazed unit can last. Most of mine have been extremely long lasting, indeed some from the middle 1970s! Yes they are narrow gap, but are still good. One has a tine crack and I suspect moisture is inside by now. The modern ones though do seem less robust. I guess if they last too long though, nobody would buy a new one... grin. Brian
The toughened glass ones can be vulnerable if they get a tiny nick on them and then with heating and cooling the crack elongates. The sort of thing that a stone thrown up by a lawnmower might inflict. You will never find it after the thing has gone pop you you can sometimes see such damage when cleaning the windows (or car windscreen). I do have one window with a visible stone chip but so far it has held out.
One of mine in normal glass double glazing has failed about a decade after someone broke into the house by forcing the adjacent opening window. I presume the stresses cause by deforming the aluminium frame and steel reinforcing eventually got to the glass and it went ping in the hot sunshine. If the frame itself is being deformed by the building moving then all bets are off. Glass is not really very flexible (though it bends by more than you might think). My greenhouse failed that way.
Not sure that modern units are any more or less robust than the older ones. The seal and insulation they achieve has improved somewhat though.
replying to Dave Chapman, DeeJayLeGrand wrote: If you look at Nickel sulphide inclusions - the location of failure starts with a "butterfly". Good to see that company is replacing the glass panels. This is impuirty in the glass production process - more common thatn you think. The breaking into small pieces is by design - what is referred to as safe breakage (by design for some glass types).
They fail due to the air/gas inside heating up and expanding. Bigger gaps have more air & therefore subjected to higher pressure.
Gay-Lussac's law: the pressure changes the same with temperature independent of the volume. Bigger gaps means more gas but also more volume.
Its harry. Scientific knowledge is not his forte. He still believes in 'renewable energy'.
The pressure might change but there?s no way it should be getting near the fatigue limit of glass unless the window is flawed in some way. Why wait a year though to pick up on an even older post? Have you joined HOH?
Tim
As I recall, Gay-Lussac's Law applies to an ideal gas. Chances an sealed unit has (at least) some water vapour in it and isn't therefore an ideal gas. The better ones are often filled with some inert gas when new, or at least dry air. However, if the the seal has failed, chances are water / water vapour had got in and a this is causing the problem. (Water vapour is a polarised molecule and that stops it being an ideal gas, if I remember my Physics.)
The concept of an ideal gas is based on theory.
You have remembered wrongly. I recall that real gasses are not ideal gasses, whether they have water vapour in them or not. However, some might approach ideal behaviour depending on the circumstances.
And in any event why would the departures from the ideal gas laws (which do of course occur) be volume dependent? Does someone think the molecules suffer from agoraphobia?
No I suspect that there is a tiny crack somewhere and at some point it just goes. There was a spate of this about 15 years or so ago, something to do with the actual glass apparently. Brian
replying to Dave Chapman, zippy101 wrote: Hi Dave, we had the same experience. Did Anglian explain the cause of why the glass had shattered?
Thanks Mark
Hi, we have just had the same problem. Inside window of double glazed roof panel blew and shattered everywhere. I was sitting under it, luckily was agile enough to move quickly, but if a child, elderly person or my animals were sitting underneath it could have killed them! The conservatory’s only 2 and a half years old, Creative View who built it all say ‘it’s common’ and say our 10 year guarantees and insurances don’t cover this (?) and want £1200 to fit a new panel!! Given there are lots of panels and they give no explanation of why or would even visit to check, I’m to scared to use the conservatory again, or let anyone else in there. Anyone know how to prevent this happening again? Do I not use heating in there (though it wasn’t on as it was 9.30am on a sunny morning and the doors were open). Or where to get protective film (as a previous post suggests). Or some sort of netting to catch the glass? Thank You
I had a Velux roof window (double-glazed glass panel) spontaneously shatter earlier this year (one of four in the kitchen) that was installed 2002-3 time-frame. It turns out this is a known problem and Velux have a formal recall programme
As an aside, the serial nos of our glass panels weren't flagged by the website checker as being covered by the recall but I sent photos to Velux who promptly decided we were eligible.
Myself I'd query the warranty not covering it. After all if it is known to be a problem then are they supplying dangerous products?When mass producing units the cost of the proper glass for the inside would be minimal I'd have thought. Besides it would be nice to know what eye mechanism for it is. Brian
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