Windows - Reaction to sun

[PeterW]

We are having problems with our double glazed windows which mist up on the sealed unit when the sun hits it. It does not look like condensation as it does not appear to be water and does not run. It is almost a discolouration of the window and stays until the sun goes down. It does not appear on windows that are not hit by the sun. Before the sun hits it is perfectly clear and it does not occur in the same place all the time but will appear in different parts of the window and in different sizes. It is almost as if it is a chemical reaction with the sun. It does not only appear to be caused by temperatures being hot on the inside or cold on the outside but occurs when temperatures on inside and out are even as well. It occured, for example, last weekend when the temperatures were hot and appeared during the course of the day as the sun hit the individual windows.
Has anyone experienced this and is there an answer.

 

[mealsonwheels]

You're not alone. We have exactly the same problem with the windows in our 2008 Swift Challenger.
Dometic have recently advised us that when this happens, to wipe the outside of the window with a warm, damp cloth. We haven't tried this yet, but intend to when the problem next arises.

 

[forestgump]

You may find this on a van thats been in storage over winter it should go over time .

 

[PeterW]

Thanks for your replys
Our caravan is a 2009 Abbey Expression, dealer special based on the Abbey Vogue. We wiped the windows daily inside and out.After a couple of days the side windows became clear,but the front three were still marked.Then the next morning the middle window was clear with the outside two marked.Our van is in storage all year round and normally we would take it out every six weeks or so,but due to the weather it was not used from October until February when it first came to light.
As we retired a couple of weeks ago we will be able to get out more frequently and will be going up to Scotland next week so will keep you posted as to whether it clears up.

 

[PeterW]

We have just returned from our trip to Scotland.Again whilst away we had the problem with marks on the windows as the sun hit them.We tried the the warm damp cloth as suggested.Over the following days the marks gradually became smaller and now seem to have disappeared.
Many thanks for your help.

 

[forestgump]

glad to help.

 

[mealsonwheels]

Hi Peter
It's good to hear that the warm, damp cloth idea seems to have worked on your windows and am glad to have passed on the info. We still haven't tried it on ours yet, but will next time it happens.

 

[waffler]

I understand the plastic is porous to water vapour but not water, like Goretex is. The warm damp cloth heats the window which turns the water in the gap into vapour which then escapes. Next bit of high humidity and the condensation will be back!!!!!. Other threads here have talked about removing the rubber bungs and using a hair drier. Anyone tried that one?

 

[mealsonwheels]

In the past, some comments have been made on caravan forums regarding bungs breaking, dropping inside windows, etc when this has been attempted,

so be mindful of this, if you take the plugs out.