Single glazed unit behind "double glazed" Vacuum G

[dishman]

Any glazing specialists around?

Will this work:

I have 1930s bay leaded lights and a box room with leaded lights. I am keeping them rather than replacing with upvc, but I would still like to make them as energy efficient as possible.

I had decided on well made/fitted secondary glazing and was happy with the pros/cons that may entail....

However, I recently came across this ultra thin Vacuum Glazing. It is produced in the UK by Pilkington under their Spacia branding. It is only 6mm thick and is designed to replicate single glazing whilst having the thermal performance of double glazing without the bulk.

So basically it can easily be retrofitted in to old frames etc.


My question, obviously you cant sandwich the leaded light between this type of glass, but, can you install it in front or behind the leaded light unit itself, within the existing frame, separated by a wooden spacer or something. Or would/could this lead to major condensation between the two? Any thoughts?

 

[Gazman16]

From what Ive read the 6mm units wont last long. Have a read of this

http://forum.expertexpert.com/viewtopic.php?f=9&t=42&sid=2573539ec31e93a26c093a8db4e5af98

 

[dishman]

Haha thats funny as I read that already and initially was concerned this was the case.

However, if you read it carefully, on the first post they are not talking about the same product. Just one which he thought was this new vacuum Glazing but then turned out to be a slim standard IG panel..............that is how I read the post.....but it took me a few times to be sure.........

Obviously I assumed that these were the welded-edge vacuum Nippon/Pilkington "Spacia" units (now called EnergiKare LEGACY).

But oh, no. And oh dear. Apparently they're just conventional IG units! But with slimmer, lesser, everything. In my experience the reduced edge seal thicknesses I've read about so far will lead to early failure and breakdown (misting and fogging). In addition, installing them with traditional putty, in a solid-bedded configuration, will accelerate the failure.

That reads to me as "he thought the ones they were using were these new glazed units (the Pilkinton Spacia) but turned out to just to standard thing IG which will fail"

So I think you may have also mis-read the post

 

[Gazman16]

If you read on (It does go on a bit but they do talk about several different makes) The main problems are the drainage, ventilation and the up stands that protect the edges of the units.

I did have a quick google and look at the Pilk's site but I couldn't find any mention of garentee, Any idea how long it is?

 

[Gazman16]

Just had time for a slightly longer look. I could find no mention of garentees or the seal at the edge of the glass.

There are a few company's out there that make good quality timber windows that are properly designed to accommodate double glazed units but very few reputable company's that would retro fit units into old windows.

I have seen hundreds of failed units in timber windows so I personally would avoid.

If you really want to keep your original windows Stick with the secondary glazing or talk to some company's about making new sash's that will take a conventional DGU.

It would well be worth contacting the chap named Goodwood from that link. He is an expert in timber windows and has his own factory, I would highly recommend him.

 

[dishman]

I still think they are referring to all the different manufacturers of standard slimline IG (traditional double glazing sealed units) which although slim are not suitable for traditional windows......... not this new method by pilkington which has a welded edge and is only 6mm thick!

They mention it has a 10 year guarantee on their site. It also mentions it has been designed to fit into standard frames with putty.

Like I said, I don not think I could use them anyway for the solution I am proposing, but worth a check.

 

[Gazman16]

Try joining and posting on that site about them. Its a very quite forum but the guys there really know the technical side of things, Id be interested in what they had to say.

 

[BTCC]

Pilkington Spacia is a unique product and shouldn't be under estimated. It's actually made in Japan so shipping adds cost. But the cost is off-set by less labour needed to deepen the rebates of original Victorian style windows. I've installed in into period properties many years ago and it is still working well. The spacers between the glass are practically invisible (unless you stare at it from a few inches away) and the cap can be placed in a corner of the pane where it will be hidden behind curtains etc.

 

[ronniecabers]

Taking out the potential issues ( or non - issues ) of Pilkington Spacia ( I would be worried about the ' vacuum ' side of it personally as it would be ' pulling ' on both panes of glass.....and sealed units and putty has been considered a big no-no for many years ) . I wouldn't install a sealed unit in front of or behind another piece of glass like that . You WILL end up with condensation and bugs/spiders living between them especially with traditional stained glass as them pesky bugs/spiders / water vapour get through the smallest of holes....

 

[BTCC]

I agree, putting two panes of glass together without a means of ventilation or to clean will result in condensation and bugs etc. Also, when the condensation starts to act on the lead it will cause discolouration and staining.
In my experience premature failure of normal sealed units is almost always due to bad fitting. Maybe we should define here that a 'normal' sealed unit is 2 panes of glass held apart by an edge spacer that is filled with dessicant and with the gap filled with air or an inert gas.