New UPVC Windows - condensation?

quietheart

We've just had new windows. Last night was the first cold night, this morning my son's room has condensation on the glass. Mainly on the outside but some on the inside. I didn't expect this from new windows.
http://i199.photobucket.com/albums/aa147/withnail1969/feb08007.jpg
What do you think?

maninthestreet

Do you mean actually inside the sealed units, or just on the bedroom side of the window that can be removed by wiping with a cloth? If the former, the units are defective and need replacing. If the latter, this is considered normal, particularly for a bedroom - DG will not eliminate condensation, but can reduce it. In a bedroom, where somone is present for 8+ hours, the moisture from their breathing increases the moisture content of the air in the room, leading to condensation on cold surfaces.

quietheart

Thanks for your reply.
Most of it is on the physical outside of the window, ie when i open the window and touch outside. I don't think it's inbetween the glass. There's just a bit on the inside.
How does the condensation on the inside of the room create water on the outside of the window? Sorry if that sound dim!

roddydogs

If you read the small print on your contract you will find "we dont guarentee to eliminate condensation" or similar

maninthestreet

rovers wrote: »

Thanks for your reply.
Most of it is on the physical outside of the window, ie when i open the window and touch outside. I don't think it's inbetween the glass. There's just a bit on the inside.
How does the condensation on the inside of the room create water on the outside of the window? Sorry if that sound dim!

Why are you concerned about condensation on the outside of the windows??
The outside glass surface is colder than the surrounding air, hence you get condensation at the glass/air interface. The glass is colder as the small, sealed air gap between the two panes of glass acts as an insulator, preventing heat from the bedroom escaping to the outside. Your DG is working as expected.

swebb

We've just had some new DG windows. Sometimes there is a little condensation at the bottom of the window (on the outside of the glass - inside the house). Nothing to be worried about. The previous windows used to be soaking in the morning!

We had a window replaced because of a fingerprint on the inside. Check your glass is clear!

quietheart

maninthestreet wrote: »

Why are you concerned about condensation on the outside of the windows??
.

I've never experienced it before in the previous 3 houses I've lived in with DG that's all. I just wanted to make sure it's not something I need to mention to the Installation Manager who's coming out in the morning.
Cheers.

Debt_Free_Chick

Double glazing is likely to increase condensation - that's why they fit "trickle vents".

If DG is aimed at trapping heat inside, then it follows that the glass will often be warmer than the air temperature outside. When that happens, you'll get condensation unless you increase the ventilation.

On the outside doesn't matter.

maninthestreet

Note that since about 2002, all new DG units are fitted with K glass, and this can make condensaton on the outside of the windows more likely compared to older DG units not fitted with K glass.

sashman

rovers

From the pic its not clear, old problem was condensation on the room side glass surface, broken unit if its between the two panes of glass or a new problem called external condenstaion if its outside glass surface.

First off, warm air contain (holds) more water vapour than colder air, thats why condensation isnt normally present in the day as the air gets warmer it evaporates.....

when the air is cooling , the vapour looks to dump water onto the coldest surface, with single glazing it was the glass.

Only cure is to ventilate the room to exchange the cooling humide air with new air from outside (even if its cold air needing to be warmed, it'll be less humid).

Condensation between the twop pieces of glass, suggests the sealed unit if faulty or broken down. When the unit is made silica jel crystals are inserted to remove the trapped moisture, before the sealant to applied. sometime a seal has a small hole that allows moist air back into the unit. Your window supplier should cover units for at least 5 years sometimes longer.

Lastly, if its on the outside it may be whats known a s external condensation. Where really thermally effiecent sealed units are used, the outside surface is cold (remember its now saving much more heat than standard sealed units) so the damp air goes to the coldest surface, brick, render or glass , if the glass is the coledst spot then thats where it'll dump the water vapour.

Hope this helps but the GGF Glass and Glazing Federation have good info sheets on condensation at www.ggf.org

Good luck

sashman

quietheart

Cheers Sashman, that makes sense to me. It is definitely external condensation. Thanks for explaining it.