View Full Version : Infiltration via Canister Lamps
I have heard from many sources that most ceiling canister type lamps are a big source of air infiltration from the attic (1 story house). Also I read about a method of constructing airtight boxes around the lamps in the attic, which I think has approval from some experts:
"A Recessed Can of Worms" by Larry Armanda and Steve McCarthy
Fortunately my house has only 1/5 the number as the one in the article, but each one seems to have 1-2 sqin of leakage designed in quite deliberately. When my house had the blower door test, this is one of the things they wanted to fix, using a different method and a price I didn't like at the time.
Since this sort of edges over from the HVAC trade to the construction trade, the subject seems to be awkward for this site but I cannot find a better one. Has anyone had experience with this method, perhaps used it themselves?
Thanks to all who care to respond! -- P.Student
01-18-2005, 10:52 PM
You have a couple of options:
1) You can build an air tight box of noncombustible materials over each of the recessed lights. If each one of them has the thermal protection it will be safe, but the lights will turn off when they overheat. If they don't have the temperature sensor it may overheat and start a fire.
2) You can replace each of the recessed lights with an air sealed can. Off the top of my head these will run you less than $10 each for the can. Installation will cost extra. Last time I checked Home Depot didn't know what air sealed recessed lights were. You will have to call around to find them.
3) You can leave them just like they are and know that there is plenty of cooling air passing through those lights. You just don't know if that airflow is helping or hurting you/your family.
We try to remove recessed lights from unconditioned spaces in all designs. When the Owner really wants them, we strongly recommend air sealed lights. We end up retrofitting a lot of the unsealed lights when the Owner figures out how much they leak.
01-19-2005, 08:35 AM
Student, you are really learning fast how a home works. Minnesota Department of Energy first wrote up “Leaking” Recessed Lights in the fall of 1992! They have written many other articles (which I maintain in my library on IAQ) on topics’ finally being discussed here, that is why I enjoy reading about all these “NEW” problems in homes today and all the Rube Goldberg Fixes.
If the Lights are IC and have a thermal cut out, my KISS fix is to go to the nursery and buy the Styrofoam rose bush cones large enough to fit over them with proper clearance around all sides. Put a little caulk around the bottom, peel back the insulation and stick it to the drywall or ceiling. Replace the insulation and then I suggest you take a pencil and poke two holes in the top to allow air to enter and exit.
Good Luck and continue learning about all the new/old opportunities in today's homes.
01-19-2005, 08:54 AM
Xavier, go to the States website http://www.michigan.gov/bccfs and download the new Michigan energy code which goes into effect 2/28/05. It specifically addresses recessed lights now and maybe in newer homes and remodels we will finally take care of this problem. As for older homes time and education of the public will hopefully take care of the problem, but I highly doubt it.
01-19-2005, 09:30 AM
Actually there are 4 methods. The easiest being a powerlux flourescent insert kit. Go to http://www.powerlux.com
In this case Xavier's proposal is simple enough, but that would probably have its drawbacks due to the flammable Styrofoam material. It is my understanding the sheetrock box design is to avoid 1) excessively high temperatures and 2) flammability. Could certainly stand to beef up my understanding of what formal experts say, e.g. if building codes ever specifically address this.
Tentatively I am planning on building the boxes out of sheetrock, plus convert to CF lamps. According to that research paper I cited, the resulting temperature in the box would be no higher than ambient(!). Still, this is the first time I have thought about doing something like this and have an intuitive feeling others could give me good advice.
Thanks for the response so far and I am looking forward to more!
01-24-2005, 03:55 PM
P.Student - If I'm not mistaken, Washington state now has a code requirement for airtight cans for recessed lights. Depending on where you are in the country (if I remember correctly you are in Texas), you can pick up airtight cans, IC rated, for about 6 bucks a piece. Last week, the airtight cans were about the only thing you could buy in a local Wisconsin version of the big orange box.
01-29-2005, 06:12 PM
This has been a big subject for debate in my area recently.
There are different methods for sealing IC rated recessed lights, but the best install is an ICAT recessed light.
(Insulation Contact Air Tight)That said, there are specific kits to retrofit lights that are not air tight.
Get the name brand and model number of of the light.
Do an online search for the mfg. (Juno brand for example is made by Cooper Lighting) Using this information you can purchase air tight inserts that will seal the IC can to Air Tight standards. These inserts are based on mfg specifics to each model and are the best and safest way to seal these lights.
The Department of Natural Resources here in La. recommended using a foam ice chest (sized according to size of existing recessed light allowing a minimun of 4" clearance on all sides and top as a method of sealing these lights. Using a razor knife to notch the chest to fit snugly and caulking the chest to the attic flooring.
To this I would add installing CF's.
However if you sell your home and someone installs an incandescent light and it overheats...
So only if I were planning on monitering the type of light to be installed would this be a recommendation I would make.
Also this information was several years ago and more mfgs are now making inserts to solve this problem.
I did read the information in the Home Energy link, they as another company (zerodraft.com) both recommend building boxes out of sheetrock. Maybe an imporvement on that would be firerated sheetrock?
I would check into minimum clearance on building these boxes, and also into sealing these boxes to the attic flooring. A mastic tape would seal sheetrock box to sheetrock ceiling or even plywood.
While there are alternative solutions to this problem, my recommendation is to purchase air tight recessed lights.
If cans are not air tight install the correct insert.
If you decide to make the lights air tight with some type of air tight box, check requirements of the specific light and clearance of the box you build. And use CF's.
You are on the right track in stopping these leakage areas.
Best of luck with your project!
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