Weird condensation on inside of windows

[Chickenandegg8]

Hi, we’ve had new sliding doors fitted last month in our new extension and when it’s cold one of them has a weird circle of condensation right in the middle of it.
We’ve spoken to the guy who put them in and he’s said it looks odd but it may just be where the room is drying out. He’s said give it another few months and he’ll look at it if it’s still a problem....
Has anyone had this before?

[Roussette]

Yes. On some of my windows fitted a long time ago. Think it's normal

[BreakfastAtSquiffanys]

Have you tried giving the area and good clean and a dry?
I wonder if there is some residue on the glass

[Wildboar]

It’s probably where a sticker was. Can you try giving it a really good clean?

[PigletJohn]

do you mean on the surface into the room? Or do you mean between the two panes?

[SunnySomer]

I have the same on new windowpanes - I think they were put in place with suction cups which must have left some kind of residue. I should probably clean them properly

[Roussette]

Mine is between the two panes and is evident when the heating comes on in the morning when it's cold but quickly goes.

[Chickenandegg8]

Yes it’s on the inside.
It’s really odd. Our builder made me put my finger on the glass, he put his finger on the other side and we moved them towards the centre where the condensation is. They looked closed together...
It’s like the gap between the panes gets smaller at to the centre of the window.... which doesn’t seem right. But then I’m not an expert!

[PigletJohn]

if you are getting condensation or mist between the two panes, then you have a faulty unit. The air or gas between them is dried during manufacture and a dessicant is added around the edges before they are sealed.

If it came from the supplier like that, the installer can return it for exchance.

[Chickenandegg8]

No it’s not in between, it’s on the inside side of the window so I can wipe it away.
It’s just seems odd, we get condensation on the outside of windows, or at the bottom on the inside the room, but never in a circular pattern on the inside of the room.

[Chickenandegg8]

And it’s weird how the gap between panes gets smaller the closer you get to the condensation circle. I thought it stayed constant throughout the whole window....

[PigletJohn]

OK

the unit is sealed. When warm, the gas inside expands and pushes the panes slightly apart. this will be seen mostly in the middle. When cold, they will be drawn slightly together. I suppose wehat is happening is that they are so close that the heat loss is greater in the middle. I don't think I've seen that happen before.

It will be more noticeable if the room is humid, for example ironing, boiling kettles, excessive breathing, or wet washing.

[Chickenandegg8]

Ah ok thank you!
It’s in a new extension, we’ve not long had it all plastered and painted so there has been lots of moisture! The radiators only went in 2 weeks ago so there’s been no heat, we’ve been opening the velux but now it’s cold so we’re just leaving the trickle vents open.
Is it something that should right itself when the moisture has reduced?
Thanks so much!

[Chickenandegg8]

Oh and I guess if the panes of glass are that close they’re not insulating very well?

[PigletJohn]

the moisture should reduce with ventilation and time. Open the doors/windows when you can. If the kitchen extractor is in that area, use that too.

[chickenstrippers]

@Roussette your unit is blown if it's between the glass. You can get it replaced ( just the glass)

[user1498572889]

@PigletJohn
You learn something new every day. Thank you.

[Chickenandegg8]

@PigletJohn, does the fact that the panes are so close together mean that they won’t be insulating very well?

[Roussette]

But chicken it's gone in no time at all. It's when it's cold and the house is heating up. Maybe its on the outside and I haven't realised!

[PigletJohn]

egg

narrower gaps are less effective. I did once know the effectiveness of different sized gaps. I have an idea 18mm was best (wider ones get convection currents in the gap)

But they are all so much better than single glazing, the gap variation makes a minor difference. Thick lined curtains will help a lot.

[Chickenandegg8]

Great thank you!