condensation on glass-covered water well

Postby petracarter » Tue Apr 21, 2009 8:35 am

I have in my basement a beautiful 30ft deep, stone-lined waterwell which I've made into a feature - with a 35mm thick, walk-on, glass cover and an underwater light. We've also added an airvent with an electric pump to extract excess moisture...
However, despite the extractor pump, and wiping the glass with a diluted vinegar mixture, moisture drops still form on the bottom of the glass plate - obviously because of the difference in temperature between air and cover. These drops cannot 'run off' as the plate is perfectly level. Does anyone have any bright ideas how to stop this condensation?
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Simply Build It

Postby davewilliams23 » Sat Dec 05, 2009 2:50 pm

I have exactly the same problem, although my well doesn't have an air vent. I have tried to allow air circulation by creating a gap between the glass well top and the frame, however this was un-succesful. Wondering if you found a solution or a product on the market which would repel water from the glass? (in a form of a coating on the glass?) Awaiting your reply, Thanks.
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Postby Perry525 » Tue Dec 08, 2009 5:49 pm

Condensation forms on a cold surface.
The glass is too cold.
Raise its temperature and the problem will go away.
Find a small fan heater, like they sell for clearing a cars windscreen and aim it to blow across the glass to warm it.
Note: Condensation forms when warm wet air meets a cold surface. The drop in air temperature reduces the airs ability to hold water vapour. It drops out onto the nearest cold surface.
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Postby spinynorman » Fri Sep 17, 2010 3:08 pm

We have a brick-lined well outside, in a courtyard, which we also covered with a thick glass plate. The well is dry and is ventilated, with an old drain inlet at the top on one side and a narrower pipe we put in on the other side to try to create an airflow across the glass. It still gets covered with condensation.
I bought anti-condensation self-adhesive sheet (the sort used for shop windows or greenhouses, but that didn't work at all.
Shaving foam, the cheap white stuff, not gel, works for about 2 weeks - the water forms a film across the glass which you can see through and on a warm day it quickly evaporates. For several weeks after that, condensation forms, but doesn't obscure the glass. To apply the foam, squirt a little on a cloth and rub all over the inside of the glass, until it is clear again. A little goes a long way.
I haven't tried the heater idea. The problem would be where to put it so it doesn't spoil the look of the well. An expensive alternative would be to replace the glass with an iron grating.
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Postby IanPotton » Sun Mar 27, 2011 5:34 pm

I have just found a well in our garden, and we want to make a feature of it by putting a glass cover on, as you have done. Can you give me some pointers?

Many thanks in advance

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Postby spinynorman » Sun Jan 29, 2012 6:38 pm

Seems to be several people with this problem. I haven't found a way of making the glass cover work without condensation. I was thinking of having a wrought iron grid made, so you could see into the well but not fall in. Possibly with some kind of solid metal cover that could be put over it in autumn and winter, to stop leaves blowing in. But I expect that would cost as much as the glass cover cost, at least.
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Postby ChrisRichmond » Fri Feb 21, 2014 5:43 pm

Why not lay a soil warming cable around the edge of the glass so the glass sits on it, cushion it with either a bed of mortar or better still silicone.
This will then heat the glass stopping the condensation forming and not only is the cable water proof it is also very economical to run especially if you get one with a thermostat.

Cheers Chris ... d7984.html
Link as example
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