Kirstie Allsopp, in Loc, loc, loc... "It's cold up there and these ceiling lights get hot and are causing moisture to condense around them on the ceiling..."
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15 years ago
Interesting take on physics
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15 years ago
Seems clear enough to me. Do you need some help with the explanation?
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15 years ago
But did you see that there were TWO patches on the ceiling?
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15 years ago
Yes. I would expect the heat to cause any moisture to evaporate - not condense!
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15 years ago
I didn't see it at all, however I would expect one either side.
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15 years ago
One round the ceiling light fitting - the other to one side - almost a figure-of-eight. IMHO there must be two drips (or something) to cause that pattern.
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15 years ago
Yes but what were the chances of water drips droppig on/around the light? million to one chance.
I reckon it was bathroom at one time?
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15 years ago
Far more likely that the slight heat from the lamp causes convection currents and something is making cold spots.. condensation. Condensation causes most damp problems. Made worse when the unknowing add heat in the form of bottled gas heaters.
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15 years ago
But it must have fitted properly with one of those fire resistant upside-down plantpot things. And that would inhibit any such convection. Surely... :-)
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15 years ago
I didn't see the show, so this is pure supposition. If, as implied in the statement, the ceiling is colder than the room air temperature then a warm light could draw up moist air and that impinging on the cold ceiling surface could result in condensation.
Colin Bignell
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15 years ago
How does a warm light draw up cold air? I would expect a source of heat at the ceiling to create a layer of warmer air next to the ceiling (remember that heating a gas causes it to expand).
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15 years ago
Attic room. Ceiling goes across below the apex of the roof. At a guess about four feet wide and ten feet long. (Even if not accurate it gives a working idea.) Somewhere near middle of ceiling, downlighter. Not sure if LV or mains. One ring of damp around the hole where the light fitting is inserted into the ceiling. A second to one side - I'd guess 45 degrees to direction of rafters away from first ring. There is a Velux (or similar). Roof apparently good condition concrete tiles.
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15 years ago
Ah. Given that the downlighter probably allows air flow through to the apex space, I would imagine then that hot air is rising into the apex drawing colder air from the room below.
Tim
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15 years ago
Concrete tiles?
Lets just Kirsty was right because she'd have looked rather stupid if she was talking bollocks. These progrs are recorded and then aired are they not? so therefore she'd have got an opinion on the damp also.
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15 years ago
hmmmm I think you may be giving the program makers way to much credit.
Someone may indeed have got an opinion but it does not mean that the presenter understands it or presents a good explanation.
OP /Quote Kirstie Allsopp, in Loc, loc, loc... "It's cold up there and these ceiling lights get hot and are causing moisture to condense around them on the ceiling..." /end quote
This is indeed bollocks. The lights getting hot in themselves does not cause the moisture to condense. It being cold and having hot lights does not necessarily cause moisture to condense.
Having a localised increase in water vapour, and a route into a cold space (with no ventilation) will result in condensation forming in the cold space.
It does sound like someone has said the patches are due to A, B and C... but her interpretation and communication of this is lacking. However having not seen the program I do not know exactly what she is referring to in the context of the OP's quote so some of this is conjecture.
cheers
David
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15 years ago
The hot air then hits the cold roof and cools and falls to be replaced by more air drawn up. If it were *well* insulated what you said might be true.
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15 years ago
Or hot air is rising into the apex and then condensing on a cold surface and dripping back onto the ceiling.
MBQ
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15 years ago
How does the light (up high) heat the air (low down) sufficiently to cause the temperature inversion necessary for convection to start? If the light heats anything, it will be the air up high near the light, thus creating a layer of warm stagnant air at the top.
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15 years ago
chaos theory? Are there no draughts, or any other irregularity to start it off?
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15 years ago
We were somewhere around Barstow, on the edge of the desert, when the drugs began to take hold. I remember DM saying something like:
That's pretty much exactly it, I believe. It's possible that drips were forming on the rafter above the light, but who knows.
It just sounded like so much bollocks when she spouted it - now we'll have a whole generation of TV property programme viewers and/or dodgy builders who will nod knowledgeably and say something like, "It's the ceiling light that's condensing the damp, luv", whenever they spot a patch on the ceiling.