Down lighters.....condensation......

[limerockconstruction]

Hi Guys,

I have a small problem that has occurred in a large extension I have just done; I only mention large because I wondered if the mass of new insulation is relevant. 150mm in floor (UFH installed), 125mm between roof timbers and 25mm under, full-fill in the cav (thermalite and conc 300mm). Extension is 45 sq.m

We installed numerous down lighters as seems to be the fashion at the moment, and in a couple of them since the cold weather has arrived we have started seeing condensation drip from the actual fittings.

The sparky fitted them in the traditional way, ie; cut his holes in the celotex etc

One half of the extension is a family room where one light is quite bad, and one in the kitchen which is also quite bad.

The sparky has just said that when this happened in the past he just stuffed the eaves with rockwool to cut off the air flow - surely this isn't the right way to go?

Any thoughts would be appreciated.

 

[Markerpen]

Hi
Downlights can be a real condensation problem. If these are the open type, ie virtually a bulb in a hole, these can funnel moist air up into the roof space, aided by the warmth from the bulb.
No - rockwool in the eaves, and no covers over the lights, they would overheat.
If the lights are of that type - if you take a close look there is a gap all round the bulb. One way to solve is to use IP44 rated lights, as used in bathrooms, or fire rated fittings, although these are not so sealed as IP44.

Just do not do what your sparks suggested.

 

[JohnD]

you can put a smoke hood over them to prevent warm moist air rising through the hole. You can also use clay flowerpots, or make up plasterboard boxes - both of these are fireproof.

what sort of lamps have they got? hot or cool?

are these horrible holes in the ceiling just going into the loft?

 

[limerockconstruction]

Thanks Chaps.....

Out of interest how would the IP44 lights solve the problem, what are the differences between the and normal down lighters?

Also, i've never come across smoke hoods before? How easy are these to fit retrospectively?

I'm up for doing whatever the right thing is, just want to make sure the one I choose is the right one, I don't mind revisiting the job for things, but it would be nice if I only have to do it once for these!

Just an after thought, if I only treat the 2 that are the problem, is that good enough, or will the problem spread like wildfire?!

 

[dann09]

I'd go along with what's been said, excepting that i'm a bit leery of smoke hoods, but thats just me.

Is this a pitched roof and do you have access to it? If so, have you had a look into the roof space for any further condensation issues.

Dont now or ever block ventilation without expert opinion.

Why these D/L's and not the others, is there some pattern? Something changed recently?

 

[dann09]

Just noticed your last posting. Are you the builder or the householder?
Condensation doesn't "spread like wildfire". Google smoke hoods and IP44's. Pics will help you understand.

 

[limerockconstruction]

Hi Dan - thanks for the reply - its a lean to roof ie; back into the main house, which I would only have access to from above as we finished the job a few months back now - its got a vaulted ceiling inside, we used roofsheild breather membrane so I imagine there aren't any condensation issues other than the mentioned....

In terms of the pattern - a complete mystery i'm afraid at this stage!

In terms of your question, i'm the builder, just a little naive on downlighters. My remark was a little flippant, I didn't mean it to sound that way, I just wondered if Iresolved the issues with just these 2 lights, would the problem maybe spread up to the next light up?

 

[JohnD]

yes, because warm humid air will continue to rise into the roof space from the other lamps.

It's my guess that there is a lot of condensation up there, but you are only conscious of what by chance is dripping through the holes of those particular lamps.

 

[dann09]

Thanks for your reply and John's info,

What do you mean by gaining "access from above" ... do you mean by coming through the upper main house wall, or opening up the lean-to roof?
Is there an in-situ trap somewhere? How would the sparky have "stuffed the eaves"?

I'm familiar with hanging vaulted ceilings, but never in a lean- to. I presume that it's a shallow vault. However, the spaces behind the sloping cheeks might be difficult to ventilate.

 

[limerockconstruction]

sorry for the confusion - we often just use the term vaulted ceiling to define a sloping ceiling that follows the lean too roof line - so essentially just a sloping ceiling.

In terms of access, yes I meant just from above, ie picking back the tiles and felt and batten etc.

Edit; I also think the sparky literally meant to stuff the bottom of the joists near the gutter with rockwool - didn't go into to much detail with him because I didn't like the sound of it.

 

[dann09]

So, in essence, you have an arrangement similar to a flat roof installation only the D/L's are fixed at an angle. You should contact the Mfr's for further advice, perhaps scan them a section drawing of the roof, and maybe post in the Electrical Forum.

 

[catlad]

I have one of those small inspection camera's made by bosch 10.8v it may be worth getting yourself one, and then take the lamp out nearest the problem one and have a look, you can get a lead that attaches to the lap top for a bigger picture. It sounds like a recipe for condensation though without any thing above the lamps in such a cold spot.

 

[dann09]

Great call catlad, i know that i wouldn't have thought of a camera through the can.

 

[ASDAPrice]

If you have a col void behind the fittings, with not much ventilation, then even fitting IP rated or fire rated fittings or using fire hoods isn't going to solve the issue.

Its always going to be an issue when you have a lamp running hot for a period of time, then after switching off cold air condensing on the warm surface.

Also, can never understand installing downlights in voids that are full of celotex etc, you spend the money on insulating then start cutting it out to fit the lights??? The best way would be to construct a deep enough ceiling void or structure that would accept downlights with out having to interfere with your insulation board.

 

[limerockconstruction]

ASDAPrice - i'm with you, i'm not sure why people do it? Would have thought there was some official solution to the problem, perhaps the manufacturers have some idea?

I think I may well bear the 'false ceiling' idea in mind for the future - so long as space allows it. (suppose I could split the difference and just chop into the insulation a little bit and only have a 50mm false ceiling?)

Thanks all