Posted By: MarenPrice Update:

The U-value for these alu-clad, double glazed windows is given as 1.4 (average), these are the only windows
built 6-22-4 with warm spacer (and argon filled).

Monty: thanks for your concern. I posted the Nordwin catalogue in response to valasay to show that Nordwin was the particular name given by the Hermann-Gutmann-Werke to the same aluminium profiles discussed earlier (Braga and Mira) as made specifically for the Scandinavian/British market. You are right of course that this says nothing about the actual timber frame or glazing units.

Do you have any insight on the Rationel windows?

22mm is quite a bit wider than the optimal 16mm cavity for argon filled units resulting in poorer centre of glass values – 1.2 as opposed to 1.1. The Rationel website is not particularly helpful as it provides the same u-value for a whole slew of window types leading me to think they are giving the data for a fixed light (more glass, less frame, minimal air leakage).

My concerns are directed at the particular company mentioned in connection with the importation rather than the Nordwin system. Fortunately the introduction CE marking, which will show the manufacturer amongst other things, will take care of this issue early next year. Anybody buying imported windows that are not CE marked would do so at their own risk.

They are good windows. A few points to consider;
If you require the Secured By Design standard then it is an upgrade. So are fully reversible windows. This specification may be different in the UK market.
One irritating issue with these windows is the propensity for the external glazing gasket to work its way loose. I’m not sure if this has been designed out yet but it’s not an un-common site here in Ireland to see the gasket dangling in the breeze.

Monty

There is no question about the quality of Rationel products and they certainly do have CE marking in place. It’s the like of Rawington who I would like to see certification for.

Rationels U-value information is not exactly a model of clarity though.
The CE marking on their website gives a standard u-value of 1.3 W/m²•K for an ALDUS sidehung window, yet qualifies this with “The value is calculated for a single window 1230 x 1480mm with Rationel 4-24-4 standard glazing” (The maximum width that they will actually make a sidehung window is only 948mm!) Their architects brochure though states u-value for a “standard ALDUS size (1230x1480mm) is 1.44 W/m²•K.

I know this may sound pedantic but to anyone familiar with these issues something sounds a bit odd. A 24mm cavity using a Pilkington SN or S3 coating (they may be using a Guardian 1.0 IGU but again their published g values - 0.63 - don’t support this) will give a centre of glass u-value of 1.1 with a 16mm argon filled cavity. Increase that beyond 20mm and the u-value goes out to 1.2. Its very hard to see how they can achieve a whole window u-value of 1.3 when the glazing is coming in at 1.2. Unless of course they are using the data from a fixed light somewhat larger then 1230 x 1480!

I would be curious as to what third party certification there is for the unit u-values you were given. You might ask the supplier to check.

Anybody else have any suggestions as to how they are getting these u-values?

Monty

As the industry adage goes “Tell me the result you want and I’ll tell you where to do the testing”
I’m surprised that you’ve come across people under-estimating – its not an industry renowned for selling itself short.

I had hoped CE marking would clarify this issue but given the Rationel example (and others) it doesn’t look that way. The continental manufacturers by and large take the EN10077 standard of 1230x1480 and measure a single light. This is not a problem with tilt/turn windows or some of the H-Type hinges unlike outward opening casements typical in the British Isles which would have a problem supporting a sash of that size. UK manufacturers stick to the GGF 2.2 configuration of a 1230x1480 frame divided into an opening sash and a fixed light as suggested in BRE 443.
A single fixed light will typically perform better then a single opening sash which will perform better then a combined sash and fixed light (due to a combination of perimeter air leakage and glass to frame ratios).

BFRC certificates are going to muddy the waters even further. PVC manufacturers may well certify a product with minimal reinforcement – to get a lower u-value – and then end up having to insert steel reinforcement to get a stable window.

Monty

Uw 1.4 is not that far of what what I would expect to see for 3G without the argon and a mid-performance coating on one pane only on a 1.2m x 1.2m window.
Chances are its something you saw in an oldish scandinavian catalogue.

Monty

Maren,
any news?? As I am in a similar situation to yours I am following with interest.

Posted By: MarenRegarding the alu-finish: The sample window (alu-clad) spent two weeks in my house, hidden so the kids couldn't damage it. Nonetheless, when I got it out to return it I noticed a bent corner and a dent in the cladding, with the colour threatening to flake off where it was dented. I came to the conclusion that alu-cladding is ideal if you have very careful installers and nobody touches your units after installation. As we have three very lively kids and a temperamental builder, alu-cladding is not for us after all.

That's interesting - we had a sample 'corner of a window' that we sent to planning, and that then kicked around our house (literally) for about six months before we swapped it for a set of full size ones. During that time, the aluminium remained dent free and the paint remained intact. The full size units made it on a ferry from Europe and across a field via an agricultural low loader without incidence.

Kombi,

Try these people

http://www.sunparadise.co.uk/

I know some of their profiles can be triple glazed, they may have something suitable. We used them for some slidyfoldy doors & were very happy with the product.

Best of luck

Chris

Kombi,

sorry to hear about your problems, our windows are expected for the week starting 15 Feb so we're still waiting.

Just had a quick look through all my quotes - Albo Uk and Nordan quoted for a triple glazed door set similar to the window set you require, Rawington was double glazed - can't remember if they could do the triple glazed sliding. Our 4 sections were 700 mm each, though, and a number of companies told us they could not make sliding doors that small due to the weight I think - which is why we went with the french doors instead (also worked out at least £1k cheaper for the manufacturers who did offer this door set)

Hope this helps.

http://www.albo.co.uk/
http://www.rawington.com/
http://www.nordan.co.uk/UK/index.php

I found this thread extremely useful when starting my search for windows last summer for a major self-build refurb project, thank you Maren for the original comparison of suppliers. I spent a long time researching and selecting my windows, 6 alu-clad timer, 2 external doors and french doors, approx 14 sq m total, plus 2 roof-lights. Roof-lights were easy, only Velux offered the spec, size and finish I wanted, and Jewsons gave me the best price.

My initial request went to most of the list Maren mentioned, plus a few others. I was impressed with the speed of response from Nordan, Rationel, Rawington, Russell and Velfac, with most quoting within a few days, despite it being summer holiday period. Some of the other suppliers were much slower, but it took me longer to select a window with the normal delays caused by changing the size and location of windows.

I was looking at design and quality of windows and doors, plus confidence in the supplier, with price not a major consideration provided it was within my budget - I was asking for supply only with option for fitting. After viewing windows (I live within an hour or so of showrooms for RationeI, Rawington, Velfac and Nordan, and visited an impressive Adpol project) I reluctantly dismissed Russell as there were no windows or projects I could see locally, as well as Adpol as the appearance of the windows just wasnt to my taste. Nordan, especially the doors, were expensive but extremely high quality though I thought the others looked better. Eventually Rawington offered a superior design, not in their catalogue, with central mullion to match other older windows. My original spec inevitably changed, notably to a sliding patio door as well as the central mullion on the windows.

Prices? For the original spec there was a wide spread, from £310 to £550 per sq m. Rawington quoted £410 per sq m. All these were plus delivery, installation and VAT.

I placed order in end October. My windows were ready within the stated 7-8 weeks but bad weather prevented delivery until early January.

What impressed me about Rawington? Technical support before order was excellent, with most emails answered the same evening. Information on delivery arrived without having to ask for it, and I was even sent a picture of the completed windows ready for despatch. Installation was meticulous on a Sunday and Monday, and a return visit offered to carry out adjustments - there will be a few, but nothing major. Window quality and finish is as good if not better than their showroom windows, and upto the standard of the Velux windows. (My job was in manufacture of building products)

Negative points? Compared with Nordan, Rationel or Velfac, Rawington are a much smaller operation in UK, so the comfort factor is lower, but offset by the ability to deal direct with the person that runs the UK operation.

Having seen a lot of windows, if I were starting my search again, I would limit it to windows I could see, because I found the windows had to be viewed to compare appearance and ease of use.

Hope this helps the next person looking for windows!

<blockquote><cite>Posted By: Peter65</cite>
Eventually Rawington offered a superior design, not in their catalogue, with central mullion to match other older windows. My original spec inevitably changed, notably to a sliding patio door as well as the central mullion on the windows.

What impressed me about Rawington? Technical support before order was excellent, with most emails answered the same evening. Information on delivery arrived without having to ask for it, and I was even sent a picture of the completed windows ready for despatch. Installation was meticulous on a Sunday and Monday, and a return visit offered to carry out adjustments - there will be a few, but nothing major. Window quality and finish is as good if not better than their showroom windows, and upto the standard of the Velux windows. (My job was in manufacture of building products)

Hope this helps the next person looking for windows!</blockquote>

Peter, was there any indication on the windows or packaging to indicate who actually made the windows and what country they were made in ?

The Rawington website does its best to infer that the windows are made in Germany by Gutmann AG.... who errr.. don't actually make windows! They are a systems producer. ie. they sell window systems to fabricators or joinery companies who actually make the windows.
What warranty did you get (not from Gutmann for sure) and was it provided by the manufacturer ?

Monty

Can someone who has lots of windows and door specs to hand give me some idea of expected weights? e.g for 2.0*.9m 2G or 3G fully-glazed door and 1.5*0.7 windows.

You can easily work out weight, dominated by density of glass (x area x thickness x no of panes) + a minor bit for the timber frame, or calc that too. Just get the figures to hand and henceforth work it out in seconds.

<blockquote><cite>Posted By: wookey</cite>Can someone who has lots of windows and door specs to hand give me some idea of expected weights? e.g for 2.0*.9m 2G or 3G fully-glazed door and 1.5*0.7 windows.</blockquote>

1sq/m of 4mm glass weighs 10kg.
1sq/m of 6mm glass weighs 15kg.
Standard double glazing is typically two panes of 4mm so weight is 20kg sq/m
Laminated glass is typically 6.4 mm so 40kg sq/m (or 30kg if 4+16+6.4 as often used in Scandinavian doors)
+50% for 3G
Frame as noted above is only a few kg

Monty

Also, anyone know how much timber choice can affect U value? According to Adpol the difference on their AluClad triple glazed unit is huge:

RED MERANTI: 0,78
PINE OR EUCALYPTUS: 0,82
OAK: 0,92
LARCH: 1,1

This post was very helpful for us and it was one of the ones that lead us to Adpol. We saw several window providers and got several quotes. In the end, we put our money down (in June 2012) for Adpol. It wasn't the cheapest quote but neither was it the most expensive.

It's October now. I'd like to tell you how the windows are, but we still haven't received them yet. ;-)

I've written about our experiences with Adpol here:

http://my-experiences-with-adpol-windows.blogspot.co.uk/2012/10/why-i-am-creating-this-blog.html

in case it's helpful to others.