Hello,
I’m installing some can lights (new construction) and I want to prevent warm air from escaping into the attic above. The joists they sit in will be filled with cellulose which will help with air movement somewhat but my current house has terrible problems with air movement through the can lights so i want build a sealed box around these new ones.
I’m not totally clear about the “rules” regarding can lights and heat buildup. I want to build boxes around them and then seal the box seams with spray foam or caulk. Can I build the boxes out of any material? Wood? XPS?
“airtight trims” can be bought for the lights also but not sure how dependable that option is, any thoughts on that?
BTW, the cans are rated IC
Thanks in advance
Replies
Use IC air tight cans. They have sealed housings and the trims seal up to the ceiling.
Since they are IC rated.... build away.
If the fixture is rated IC, it means that the thing is designed to handle the heat buildup when surrounded by thermal insulation (batts or loose fill). The fixture has a heat sensor in the housing and it'll cut off the power to the lamp if the temperature gets too high.
If you build an airtight box around the fixture, keep that in mind. With real tight fitting and well-sealed box, surrounded by thermal insulation, the heat buildup may cause the thermal cutoff to cycle the lamp off (the power comes back on when the fixture cools off).
Some cans are rated AT or airtight by the manufacturer. They aren't really completely air tight, but air leakage is low. The AT cans need a special baffle or trim ring and gasket, or both, to cut air flow to a minimum. If the cans are not AT, but are retrofit cans, it'll probably be easier and cheaper to remove them and install ICAT cans, and forget about building boxes around each fixture.
FYI, Halo lighting now makes an LED lightsource module that retrofits into their common 6" cans. Line voltage, dimmable, gives light equivalent to a 65W incandescent, not blue at all. Uses about one-eighth of the energy of an incandescent. I've got a job scheduled to install some retrofit cans and I hope the client will go for the LEDs...not cheap at c. $120 each, but last a long time and save a lot of energy. And from what I saw in the showroom, not as much glare as a fluorescent can with TT lamp (bi-pin or 4-pin).
Cliff
To anyone else that decides to post a reply.
Please read the original post.
THE CANS ARE IC RATED!
I built mine out of 1" pink foam board. About 12x14 sized to make the best use of the foam sheets. Put them together with foil tape. You can then cut slots with a drywall saw where they fit down over the brackets. Shoot foam in a can under the edges and press it down. You have to have a slot for the electrical wire to come through unless you can run it with one of the bracket legs. Believe me these are air tight. You can't run a standard bulb in them because they will over heat. But LED or florescent will work fine.
Thanks all,My concern was that if the can lights were completely sealed above they would create so much heat that building the boxes out of wood or foam might be dangerous but it sounds like I won't have any problems as long as they are IC rated.
Nooo, IC rated means they can operate and not overheat when in contact with regular batt or loose fill thermal insulation. You build an air tight box around 'em, and the heat build up may be too great, causing the fixture to overheat and cycle on and off. Previous post bears this out, he had to use fluorescent or LED light source as icandescent overheated the fixture.
If you plan to use non-incandescent lamps, fine, but what about a subsequent owner or resident? What happens if someone relamps with incandescent lamps (the label on the can says that's O.K.), and the overheat sensor fails to do its job?
Cliff
"Nooo, IC rated means they can operate and not overheat when in contact with regular batt or loose fill thermal insulation. You build an airtight box around 'em, and the heat build up may be too great, causing the fixture to overheat and cycle on and off."
Thank you, that is the info I was looking for. I knew an IC can could be covered in insulation, but I wasn't sure what affect an airtight box would have on it. So it sounds like safety isn't an issue, but the function of the light could be.
I suppose airtight trim works because it blocks the air at the ceiling while the fixture can vent from the back?
The fixture can shed heat from the back. Probably a lot of that is air convection through the insulaton, even the "airtight" rated cans aren't actually completely air tight.
Happy to help. It'd be a shame to spend a lot of time and effort boxing in the cans only to find you can't run the lamp in it that you want.
One thing you could try, is put a box around one. Make it tight, but don't make it completely air tight. Run an incandescent lamp in it, and see what happens. Or if it's your preferenece, use a fluorescent or an LED module. See what happens. IF the can heat cycles with a PAR lamp, loosen up the box.
Good luck--
Cliff
IC means you can bury them under as much insulation as you can afford. If you are afraid of boxeing them in... dump 3' of cellulose on top of them.
http://www.ul.com/regulators/luminaries.pdf
Thanks for the link.
IC=INSULATION CONTACT
not exactly, the vapour barier has to have a "special rating" (sorry, too long ago to remember, check the cans, it will say on them) had huge arguement with elec inspec once, according to the elect code, there's combustable, non-combustable, and vapour barrier .. essentially nromal vb will will not burn at that temp, but it will melt defeating it's purpose ..