Down Lighters

gears

I know this has been asked before but I was wondering if there are any new products or if any one has some new ideas for solving the old problem of sealing around down lighters to improve air-tightness.

I've been given various ideas including using old biscuit tins and then sealing them with a small amount of fire rated mounting foam or high temp silicone or using clay pots and sealing them in a similar way. Any advice or ideas would be great.

Mr Magnolia

I'm not sure I follow. The area around the downlighter above the ceiling must remain clear to allow ventilation for the unit. Is this what you're looking to seal?

delly

Moved from DIY

gears

Im not proposing to seal the area around the down-lighter itself but just use something large enough to allow air to move around the unit but still cover it and give a seal to stop draughts comming through as I want to improve air tightness and once this job is complete to add additional insulation in the attic.

northdublin

i have ip rated downlighters in my bathroom that have a rubber seal between the rim of the fitting and where it makes contact with the ceiling, i would think these might be a bit better then standard downlighters and they look identical to the standard ones also

10-10-20

Gears,
I had a look at this problem in from a technical perspective, but a non-professional standpoint...

GU10 downlighters give good lighting with some caveats.
Having an unsealed electrical device perforate the ceiling space, allowing airflow past the bulb and also the significant loss of heat through the vent holes in this day-in-age, is less than ideal.

I took a section of loose plasterboard and drilled a suitable hole within it. I installed a 50W downlighter and installed the setup, pointing down, on a workbench with sufficient free air under it.
I took a 450g SMA tin which I modified to accept the mains power cable (fitting a suitable high-temperature rubber grommet) and I also made an adjustment to allow the tin to sit on the two sprung legs of the downlighter.
With this tin in place, I wired up the downlighter, ensuring that the high-temperature wires & sheath passed through to the outside of the tin (so that there was no twin & earth inside the tin) and powered it on.
With a thermocouple applied to the top of the tin over a 3 hour test period, at no point did the temperature rise above 45 degrees C. [The ambient temperature was 20 degrees C.]

Considering that an average attic can reach temperatures of over 30 degrees C, I personally consider that sufficiently large tin will dissipate enough heat to prevent the light fitting from overheating and will reduce the free-air-flow past a downlighter fitting.

It may even be possible to run insulation up to the outside of the tin without adverse affect. I'm in the process of testing that at present...


Is this a safe solution? I'm happy to the point that I have insulated the electrical cables from the tin (I can provide earth to the tin and the GU10 also), but this solution relies on the fact that most GU10 downlighter bulbs reflect the majority of the heat generated by the filament.
Fit a bulb with a poor reflective coating (read: cheap) and this all goes out the window...

builditwell

Just to play devils advocate,

Why does the Homebond manual and RECI say that you must never cover downlighters and have a min of 400mm space around it. Then again what happens when you floor the attic. just interested as will be converting attic in Jan and would be concerned about fire hazzards etc etc.

Thanks

10-10-20

Homebond & RECI are correct. Don't do this if you don't see the need or can't take the risk or want to maintain the standards...

I wouldn't install any insulation or downlighter-covers under the permanent floor of the attic, but I would insulate lightly & install covers under a semi-permanent floor. Reason being, you need to allow some heat into the converted are of the attic, but you should then insulate around the liveable area.

It's a minefield of do's and don'ts!

Andrea B.

Adding to all above guidelines, I refuse to install anything except the flamesafe design, such as the type seen here .

I have already dealt with one house fire where the RECI "contractor" drilled out joists to fit open backed lights (left some nice splintered kindling around them also), coupled with all other lights being covered with teracotta flowerpots by attic insulators. Where thy couldn't fit pot because of joists, the smashed it to fit.

I get shivers when I see the open backed type kits being sold off by large DIY outlets at half nothing.........obviously offloading what they cannot sell in UK anymore.

enmac

this article may be useful ..

sparkyjo

why not use gu10 led lights they low heat and if they enclosed in a cover you can put insulation offer them as you don't have any heat

the new version is just out and they are i think 3.5 watt and the only problem is the fact that they are not dimmable yet

northdublin

there is the option of cfl gu-10 which are available in a dimmable version and they also give off very little heat compared to normal gu-10 and dichroics

gears

Thanks for all the suggestions.

What I have is an MR16 fitting so I think maybe a modified version of using an SMA tin, possibly a large biscuit tin to enclose the transformer might be the job.

On the subject of led and cfl alternatives to a standard halogen MR16, I have spent over €00s in the last few months trying different leds and cfls as a replacement for the 25 MR16 I have and while I'm all for saving energy the light from all bulbs I 've used is terrible. So any suggestions ??

LeBash

Gears there are fittings available called fire rated or/and acustic proof fittings. They are pre sealed to a degree. There is 5 or six tiny holes in the top of the fitting. This is to allow airflow other wise you will be changing your MR16s forever.

I reckomend NOT changing to GU10. The light disapates too quickly and they build up much more heat which in turn halfs the life agains the MR16. Also the traffo has to be mounted away from the lamp. This SHOULD have a thermal cut out in it making the lights "flash" if it is to close to the lamp. I is just a safty feature.

Currently there is nothing on the market that will give better light than an MR16. CFL dims over its life and LED looks great, but only when you look at it, the beam angle is far too small, giving only small spots of light on the floor. There is a new MR16 out called an "IRC" that uses 35 watts and gives out 50 watts of light, so thats a 30% saving.

LeBash

I just read your orginal post fully. So if you are looking to throw all heat down and not let any up, there is a lamp manufactured by Osram called a ALU. This is a heat reflected lamp that sends all heat down.
If you dont have an Osram distributor near you, there is a heat shield made for the MR16 but they are expensive.