bathroom fan insulation?


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Old 12-07-15, 12:25 PM
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bathroom fan insulation?

I know bathroom exhaust fan vents should be insulated to prevent condensation within pipes. But what about the fan case itself? When attic light is on, this is what I see from the bathroom looking up at the fan:

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The sheet metal case of the fan has a lot of holes in it by design; so the air moves even more freely between the cold attic and the bathroom -- a lot of energy is wasted.

Was wondering if all these holes in the fan case are meant to be sealed or the entire case should be wrapped in fiberglass insulation?

Thanks in advance and best wishes!
 
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Old 12-07-15, 02:12 PM
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Fiberglass insulation would not be very good, think air filters, built with the same material. The question that is unanswered is, would sealing all of those hole go outside of the UL certification? Recessed lights have both IC (insulation contact) and AT (air tight) designations.

Strictly a guess here, all of those holes can be sealed. Two options, go crazy with foil tape or construct an air tight enclosure around and over the fan. Most people are now using low wattage energy efficient light bulbs so even if the light were left on without the fan it would not be a concern. With the fan running of course the enclosure is constantly being cooled.

And don't forget to seal around the perimeter of the fan installation.
Bud
 
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Old 12-07-15, 02:16 PM
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Since it doesn't look like there is a light in that fixture... I don't see any issue in sealing the holes up. If you have easy access from the attic... foil tape on the back of the fan housing would be the easiest way to seal the holes. Then you could cover with an insulation of your choice.
 
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Old 12-07-15, 02:53 PM
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Thank you Bud and PJmax! Yes, forgot to mention that this fan has no lights, just a fan. The fan lets some cold air into the bathroom through the vent anyway, so the question is if the holes in the fan housing make the energy loss much worse? Don't have any idea here.
 
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Old 12-07-15, 05:26 PM
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Leaks can move air in both directions and the cold air you feel is only half of the problem. The other half you just pay for. It's not that these holes are costing $30 a month, but air sealing is one of those win/win fixes that should be done at every opportunity. If your house hasn't been specifically air sealed you will be shocked at some of the other leaks you will find.

I do energy audits and use an infrared camera and have so many stories i could tell. Below is a web site to help those who want to go hunting.
http://www.efficiencyvermont.com/ste...ide_062507.pdf

Bud
 
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Old 12-07-15, 09:01 PM
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Very useful link Bud. Too bad more builders don't build houses like that. Most of the remedies need to be implemented at building construction.
 
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Old 12-07-15, 09:39 PM
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PJ, that is very true. Like a dry basement, many of the steps to make a really tight house need to be implemented during construction. When people worry about making their house too tight, it almost impossible to do as a retrofit. But that link still identifies many places to look.

BTW, good morning.

Bud
 
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Old 12-08-15, 08:50 AM
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Well, thanks, have never questioned the value of house insulation -- my specific question was about the possibility of sealing and insulating the housing of our small, lightless bathroom fan. These multiple holes are there for something or just byproducts of the manufacturing process? Besides, how does one prevent air draught through the vents -- the fans don't block the vents much when off.
 
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Old 12-08-15, 09:20 AM
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The fans usually have a backdraft damper at the exit of the housing and then another is usually located where it exits the side of the house to keep critters out as well. But they usually don't seal well. I recently installed a new bathroom exhaust as part of a major renovation and found a metal vent hood with a heavier metal damper. Seems like it will seal better.

As stated before, probably fine to seal up the holes you see with foil tape.

Bud
 
 

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