Cheap double glazing units

[ProDave]

Our present house was built by us in 2003. We actually paid a builder to build a wind and watertight shell including windows and doors.

 

At the time I didn't know much about what were good or bad windows, but I always thought what they fitted were pretty basic timber windows with double glazed units.  Having said that, we never had any issued with condensation or anything like that.

 

Right at the start very early on, one DG unit cracked. Even with a crack in it, it still worked well. Some time later another one broke, we don't know how.  Since we are trying to sell the house, we thought we better get them replaced, so got the local "double glazing" company to fit new glazing units to them both. In the summer.

 

The new units fitted perfectly and look identical to the original ones.  BUT now it's getting colder, we noticed if you drained a pan of boiling water down the sink, the new pane mists up with condensation, while the original two don't.

 

A test on a cold day (I didn't measure the outside temperature) with my IR thermometer showed the inside pane of the original units to be showing 16 degrees but the inside pane of the new unit is showing just 14 degrees.

 

Now this might be partly my fault for not specifying anything about the replacement units other than they must fit. But it's certainly a heads up to anyone else to be careful. It also must show our original ones were not that bad after all, probably better than we gave them credit for.

 

It's also a concern as soon we will be looking for someone to make us a tripple glazed unit with a stained glass panel in the middle, and unless this local company can explain why these units were so poor, and genuinely assure us they can do better, they are off the list.

 

[MikeSharp01]

There could be any number of reasons for the difference but its most likely to be down, obviously in a way, to the glass & its coatings (did they put them in the right way round - inside out?) and the interstitial gas Argon (approx two thirds the conductivity of air) / Krypton (approx one third the conductivity of air) / air. Things might also be worse than you think because measuring the surface temperature of glass with IR can be upset by reflections from within the room.

 

Ah and there is also the fact that the old units might have degraded a bit, in terms of gas fill since 2003.

Edited November 10, 2016 by MikeSharp01

[ProDave]

The point is, few of us know what to specify when ordering glass units. and this example just shows how much variation there can be between units that look alike.

 

In some ways it was easier when choosing the windows for my new house.  All the suppliers that quoted, provided the Uw and Ug values for each window. They were not bogged down in detail about what coatings the glass has or what gas is used to fill them, just the overall performance.  And as it happens the choice was easy, the second best in terms of Uw values (only second by a tiny margin) was also the cheapest quote so that is what we chose.

 

I guess later on when I start looking for the tripple glazed stained glass unit I just need them to quote the Ug value and then compare different options.

 

[Monty Gerhardy]

On 11/10/2016 at 09:06, ProDave said:

I guess later on when I start looking for the tripple glazed stained glass unit I just need them to quote the Ug value and then compare different options.

 

I'd ask about the warranty as well. Not sure what you'd get if you plan on incorporating 'stained glass' inside an IGU. You might be better of with the stained glass set in it's own frame (independent of the IGU) fitting within the reveal of the window frame.

[Onoff]

Seems the place to pose this question but exactly how "good" are generic DG windows?  I'm thinking not very. The reason I ask is that in draught proofing around my bathroom window  (covered in great detail elsewhere ) now it's done there's no draught per se but the air is colder near the window. 

 

 

All four sides have the insulated plaster board sealed against the UPVC frame.

Edited November 21, 2016 by Onoff

[Ferdinand]

I am not sure that "generic" has a generic meaning  .

 

Is it a telltale for good windows that they regularly get steamed up on the outside in the morning?

 

I usually just specify A Rated or the best they have. Usually the extra cost is minimal, not unlike that when they built our conservatory they put 100mm of Celotex in the walls and floor on request at no extra cost when I received a lower spec in the quote. Presumably since it would only add £100-£200 on a 12k project and came at the "clinch the business" stage,

 

Is it actually mandatory to have Fensa certification? Or is that one of those where it is just recommended? *innocent face*

 

Ferdinand 

Edited November 21, 2016 by Ferdinand

[Onoff]

Our DG windows never get steamed up.....could be that there's that many gales blowing in from elsewhere

 

I suppose my question should have been would you feel a difference standing next to a DG window in a (reasonably) well insulated wall. I guess you would? A thermal imaging camera is the way to go I imagine to be sure.

[PeterW]

Yes you will feel a difference of a few degrees - you're probably talking of a unit with a centre uValue of 1.2-1.4 so much worse than the wall surrounding it. 

 

You can  upgrade them to argon/krypton fill with low emissivity glass but then the frame will become the weak point so really not worth it unless they are blown