Replaced misted double glazing pane - think I’ve made it worse 8 December 2022 at 8:09PM in In my home (includes DIY) MoneySaving 9 replies 441 views

g0009348

Hello.  I had a misted double glazing window pane which was unsightly so took it out, measured it and ordered a replacement window glass. I fitted the new glass no problem however now that piece of glass gets really bad internal condensation compared to the glass pieces next to it.  It’s a Triple window.  It also feels a lot colder to touch than the other two.... i was expecting the new glass to be better for retaining heat inside not worse.  Are there any logical reasons for this? Could I have measured it incorrectly, maybe not as thick as the original so I’m not getting as good a seal as before? Or could there be anything else going on? Thanks

BUFF

did you order it with an equivalent or better spec. than the existing dgu?
e.g. low E coating on 1 pane? is it filled with a gas e.g. argon rather than just air? warm edge spacers?

If you did get it with a low-E coating on 1 pane could you have put the DGU in back-to-front?

g0009348

Ah, think this maybe the problem.  I've just took out one if the glass pieces next to the replacment dg unit, and can see there are two different thickness's of glass in use, whereas the one I have ordered has the same thickness.  I just assumed as the dg is so old, 10+ years, the new glass would always be better! 

grumbler

Different thicknesses make difference for noise transmission, not for heat. Gas (argon?) filling improves heat insulation properties. E-coating reflects heat back into the house - I don't think it can make difference for condensation.

BUFF

Lack of it will allow the internal pane to get colder so more likely to allow condensation to form on it. On the wrong surface would have a marginally poorer performance.

grumbler

BUFF said:

lack of it or on the wrong pane would - it will allow the internal pane to get colder so more likely to allow condensation to form on it. 

If you mean the coating, I disagree. If it reflects heat, it can be only colder, not wormer.

BUFF

Exactly, (I never said it would get warmer) a colder pane is more likely to allow condensation to form.Without a low-E coating a higher % of heat will be transmitted through the DGU, the room & pane will get colder> more chance of condensation.

grumbler

BUFF said:

Exactly, (I never said it would get warmer) a colder pane is more likely to allow condensation to form.

I thought you meant that the new unit is worse in some respect, e.g. lacking coating.

Without a low-E coating a higher % of heat will be transmitted through the DGU, the room & pane will get colder> more chance of condensation.

Now you lost me again.

The new unit is with coating, colder, hence more condensation on this pane.

BUFF

We don't know that the new DGU has a low-E coating (the question has been asked but not replied to).

A new DGU with coating would reflect more energy back towards the room (the coating is inside the cavity) hence the pane & room would remain warmer (than with one without) so less condensation on the internal pane.

grumbler

The OP was looking for "any logical reasons for" the fact that "the new glass ... gets really bad internal condensation compared to the [old] glass pieces next to it."

I see only two possible explanations (or their combination):

• new has E-coating while old doesn't have it
• old is filled with argon while new isn't

Possibly, you mean the same, but I just don't get it.