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-   -   Recessed/Can Lighting Heat Loss? (http://www.diychatroom.com/f17/recessed-can-lighting-heat-loss-52602/)

TomServo 09-09-2009 12:01 AM

Recessed/Can Lighting Heat Loss?
 
I'm remodeling and I'd like to add maybe 5-6 recessed lights in the kitchen of my 1-story house. I actually wouldn't mind a few more (along with some in-ceiling speakers) in the living room, but the kitchen is my first priority. This being a single story, the space above these rooms is unconditioned attic.

20 minutes of Googling later, I'm left wondering if the heat loss (even from sealed can fixtures) would make this a pretty bad idea. I'm in the Twin Cities (MN) and whatever I can do (within reason) to increase thermal efficiency has seemed to be worth it.

Of course, you can build boxes of drywall various other materials to further seal/insulate the penetration/mini chimney you've added to your ceiling. Cooler CFL lighting helps reduce the stack effect, but the bulbs aren't terribly dimmable. My thinking is, wouldn't you be better off not doing this to begin with? Or will the mitigation measures offset the problems? Seems like for the cost and hassle of doing recessed lighting the right way, I could buy some pretty nice flush mount and pendant fixtures.

sweaty 09-09-2009 03:31 AM

Personally, I would forgo the recessed lights and keep your house intact, especially in such a cold area as yours. You can find really elegant light fixtures that don't hang down far from the ceiling. After you put those up, you should still seal around the electrical boxes in the attic and then pile on the insulation.

Scuba_Dave 09-09-2009 08:16 AM

I put recessed lights in with CFL - IC cans = in contact with insulation
I did not have any snow melt over the cans - cathedral ceiling
I did make sure I insulated over the cans
With an attic above you have enough room to insulate/build a box
If you think that's too much trouble then go another route

I'll have 7 recessed cans in my kitchen when I am done
But there is a walk-in closet over the kitchen

hvaclover 09-09-2009 11:35 AM

Recessed lighting can cause a chimney effect that can pull the air from the space they serve.

There was a 100 post thread about the hows and whys they do this at hvac-talk. On the surface it seems to be a simple solution. It ain't .

I would wait for Beenthere to show. He's our resident building envelope specialist.

drtbk4ever 09-09-2009 11:49 AM

OK, now you have my attention too.

We just had 9 cans installed in our kitchen so am very interested to hear what other's thoughts are.

hvaclover 09-09-2009 11:53 AM

Trust me you are in for an education when Beenthere shows.:yes:

WaldenL 09-09-2009 03:29 PM

I would imagine that there's no way a recessed can can be better than no hole in the drywall, but they do make closed cans. That is a can that doesn't allow air to pass through it. For example: http://www.lowes.com/lowes/lkn?actio...00I&lpage=none

TomServo 09-09-2009 03:40 PM

Quote:

Originally Posted by hvaclover (Post 325693)
Trust me you are in for an education when Beenthere shows.:yes:

I look forward to it.

TomServo 09-14-2009 04:47 PM

I'm still interested in any thoughts on this. My electrician said not to worry, of course, but I'm sure he'd like to install some recessed lighting for me.

Yoyizit 09-14-2009 07:06 PM

Anyone have numbers on the heat loss for these lights? I know I saw a formula for stack effect in some HVAC or building handbook.
http://en.wikipedia.org/wiki/Stack_effect
"The glass bulb of a general service lamp can reach temperatures between 200 and 260 degrees Celsius (400 to 550 degrees Fahrenheit)"

Can you use a small fan to redirect the warm air from several fixtures back into the living space?

TomServo 09-19-2009 12:21 AM

Quote:

Originally Posted by Yoyizit (Post 327795)
Anyone have numbers on the heat loss for these lights? I know I saw a formula for stack effect in some HVAC or building handbook.
http://en.wikipedia.org/wiki/Stack_effect
"The glass bulb of a general service lamp can reach temperatures between 200 and 260 degrees Celsius (400 to 550 degrees Fahrenheit)"

Can you use a small fan to redirect the warm air from several fixtures back into the living space?

I think the simpler solution would be to use a cooler bulb, specifically a CFL.

Of course, you'd lose dimming capabilities. Yes, there are dimmable CFLs, but AFAIK, they still don't work worth a :censored:.

Scuba_Dave 09-19-2009 07:51 AM

I have dimmable CFL bulbs in the dining room, they do work
I'm not sure on the Mfg
The only reason I bought them they were marked down to .49

I do know a lot of the CFL bulbs will not (would not ?) dim properly
Plus they are usually $7 +/- a bulb
Not sure if the Mfg's have fixed the problems

beenthere 09-19-2009 11:26 AM

They do make air tight recessed lights.

Ask your electrician about them.

If he can't find out about, or get you any. You got the wrong electrician.

Yoyizit 09-19-2009 12:28 PM

Quote:

Originally Posted by TomServo (Post 329531)
I think the simpler solution would be to use a cooler bulb, specifically a CFL.

Of course, you'd lose dimming capabilities. Yes, there are dimmable CFLs, but AFAIK, they still don't work worth a :censored:.

Some people don't like the color temperature of CFLs, so even better would be LEDs whose color temp. is adjustable, but it'd be pretty sophisticated to be able to dim LEDs and maintain their color temp. Maybe some company does that.
http://www.google.com/search?client=...UTF-8&oe=UTF-8

But regular incands. also change color temp. with dimming.

TomServo 09-19-2009 11:16 PM

Quote:

Originally Posted by beenthere (Post 329639)
They do make air tight recessed lights.

Ask your electrician about them.

If he can't find out about, or get you any. You got the wrong electrician.

I already found the wrong electrician. He wanted to charge me $3800 to add a few outlets to existing circuits, add one new circuit, and do 5-6 recessed lights. Sure, without knowing all the details, you can't see how outlandish that is, but I don't have any doubt that I can do those same things for under $300 and a few hours of my time.

So, beenthere, I've heard tell that you're the resident building envelope guru, and you have no qualms with perforating my nice, solid, insulated ceiling with a handful of recessed lights? I certainly would use air tight/IC cans and insulate and seal them to the best of my ability.


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