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I recently bought a thermal leak detector and discovered that my recessed lights upstairs are leaking a lot of heat and causing the upstairs to be uncomfortable and hard to cool.

This is the brand and model of recessed lights I have.

They are non-ic rated but claim to be "air tight". However, the cans are still a good 20 degrees hotter than the ceiling around them when the lights are off. Is it possible to use one of these products to safely insulate them, or do I need to replace them with a more modern housing?

http://www.jrproductsinc.com/shop/pc/Tenmat-Covers-c209.htm

http://www.jrproductsinc.com/shop/pc/Can-Cover-It-c321.htm

Since these cans claim they cannot have insulation within 3 inches, would it be safe to use one the above products (or the like) to cover the cans?

If I do need to replace them with IC rated cans (which I'd rather not do, because of cost and my utter lack of experience), do you have recommendations on what to look for?

  • Another problem, which may be more important to fix, is that my attic space gets incredibly hot. I have plenty of insulation but my attic fan is burned out. Adding a working attic fan and a (fairly) inexpensive radiant shield (which you should totally look up if you haven't heard about it) will hopefully keep the attic space at a much cooler temperature – Matthew Levine Jan 7 '16 at 22:58
  • there are a lot of arguments against using powered attic ventilation. You might want to do some reading around online before you decide to commit to using powered fans. I'm not saying flat out don't do it, but rather just educate yourself on the topic first. – mjohns Jan 8 '16 at 18:08
  • Good advice. I'm hoping that a radiant barrier will significantly reduce the temperature, a working fan might improve things further, but I'll probably get the biggest band for my bug with the barrier – Matthew Levine Jan 9 '16 at 0:25
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Air Tight recessed lights might prevent air seepage from a conditioned area to a non-conditioned area, but they can't do much about thermal transfer.

Proper insulation is the only way to fix large amount of thermal leakage. However, your predicament is going to be that your fixtures are not insulation-contact (IC) rated.

With non-IC fixtures, you'll not only find

Do not install insulation within 3" of fixture

But you'll likely also find

Nor above fixture in such a manner to entrap heat

Example

enter image description here

You'll need to check the warning labels and/or instructions for your particular lights, but this all but eliminates the option of putting some sort of heat-trapping box above a fixture with such warning.

You will find it difficult to find a 4" IC rated remodel fixture. They just aren't readily available on the market, except for some speciality LED-driven models.

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These lights are not standard 110V AC lights, but use 12V bulbs. In fact, each element consists of the light fixture itself, plus the associated 110V -> 12V transformer.

In any transformer, there will be some loss of energy (no transformer has 100% efficiency), so some heat loss is to be expected. Moreover, in the manufacturer's documentation it is stated that:

Enhanced in heat dissipating cover, to provide noise free operation.

This is good, since a transformer that runs warm will make some noise or "sing". Recessed transformers will tend do this all the more, since they have access to a limited amount of air to take away excess heat.

There are several solutions to this problem. Unfortunately, isolation is not one of them, since all it would do would be to negate the manufacturer's efforts on cooling the transformers, and on the contrary get them all heated up.

Here are some ideas:

  1. Airflow could be maximized behind the recesses. The name of the game is to ensure the transformers get a fair supply of moving air, to help them cool down. Forget the lamps themselves, they will possibly leak less heat than the transformers. However, you will need to find solutions for where the cool air is to come from, where it will go afterwards, and how to get it moving. Natural convection, or forced? The first is naturally best, since less components would be used, and less noise generated (since no fans are used).
  2. Other means of heat conduction can be used. We can note that metals are (much) better conductors of heat than air - which is, in fact, quite a good isolation. So connecting the transformers to a metal strip that is then terminated in a cool spot (outside, perhaps) is a practical means of leading the heat produced to where is needs to go. This technique is called a "caloriduct", and is actually used in many laptop computers where there is not sufficient height to place a dissipator on top of the CPU.
  3. The final solution is probably not what is desired, since it would consist in simply replacing these lamps for a more energy-efficient model. LED enclosures come to mind, which will use much less energy to produce a similar amount of light. Naturally, all the energy saved is not transformed into heat, so our problem goes away. The problem then becomes locating units with a similar shape and size (4" circular) to replace the light part of each fixture - taking care to choose LEDs of a shade that you actually like. This last bit is at times the most complex part, since some people show low tolerance to some types of white LED light.

My own personal preference would perhaps go to solution #2, since it can be implemented with minimum changes. Suitable metallic elements could be aluminum or (more expensive) copper. They do not need to be rigid; instead wire or mesh can be used. Perhaps a large-gauge electrical wire such as that used to ground lightning rods could be pressed into service. Just make sure there is a firm connection between each transformer's existing heat dissipation surface and the metal - and, most of all, that no short-circuits are caused through the new metal.

  • Thanks for the info Alan. My heat problem unfortunately isn't caused by the transformers or use of the lights but by heat seeping in from the attic space above. You can leave the lights off all week and the cans will still be 20+ degrees hotter than the surrounding ceiling. It's hard to tell if there is air coming in or if the cans themselves are simply radiating heat because they are the same temperature as the surround air in the attic. I'd imagine it's the latter. I'm hoping to find out if there is a way to isolate/insulate these cans from the surround hot air – Matthew Levine Aug 1 '15 at 21:30
  • @MatthewLevine Then perhaps your question needs to be re-phrased for clarity. ;-) In any case, it seems clear that your isolation would need to be placed above the lights and their transformers since the lights are acting as radiative elements for the heat from the attic. Perhaps something on the floor of the attic? Solution #2 may still be applicable, since any metal mesh you place above them (and terminate in a cool place) will tend to lead the excess heat outwards, be it from the lights or from the attic. – ALAN WARD Aug 1 '15 at 21:49
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A fairly cheap way to improve the heat transfer from non-IC recessed fixtures is to install retrofit LED bulbs. It replaces the bulb and the room facing exterior housing attached to the can. It's typically very easy to remove the existing housing and tends to look better than using a standard bulb (IMHO). Each one typically runs from $10-$36.

They have a gasket where the housing touches the ceiling, which helps prevent air transfer if you get a tight fit. It probably wont do an amazing job of preventing radiant heat transfer, but it will likely be better than a standard bulb

retrofit bulb

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