EcoRenovator - View Single Post - Insulating a whole house fan louvered vent

mk1st · 04-11-14, 02:12 PM

Whole house attic fans are an older technology that are a good idea in theory but frequently don't work well because of where they are installed and what they are being asked to do. Typically, when the fan's not being used you will experience the symptoms that you describe because there's lots of places for air to leak down through the louvres, plus, it's just plain hot up above and the metal parts heat up.
When you use the fan, the attic vents are typically not large enough to accomodate the air from the fan, which will then result in air being pushed back down towards your ceiling and stirring up attic dust (and worse).
Doing the hinged cover that you mentioned is a great idea (there are commercial fans that have this feature) but really the best thing to do is to air seal and insulate your attic, removing the fan and sealing off the opening while doing that work. Also, the very best way to reduce your attic temperatures is to install a white or light colored roof. This is one of the reasons that metal roofs are making a big surge into residential construction. There are many attractive light colored roofs available as opposed to less attractive white shingles (don't see too many of those!)
Good luck.

04-11-14, 02:12 PM	#14
mk1st Friend of Entropy Join Date: Feb 2010 Location: Fort Atkinson Wi Posts: 17 Thanks: 1 Thanked 5 Times in 2 Posts	Attic Fan Whole house attic fans are an older technology that are a good idea in theory but frequently don't work well because of where they are installed and what they are being asked to do. Typically, when the fan's not being used you will experience the symptoms that you describe because there's lots of places for air to leak down through the louvres, plus, it's just plain hot up above and the metal parts heat up. When you use the fan, the attic vents are typically not large enough to accomodate the air from the fan, which will then result in air being pushed back down towards your ceiling and stirring up attic dust (and worse). Doing the hinged cover that you mentioned is a great idea (there are commercial fans that have this feature) but really the best thing to do is to air seal and insulate your attic, removing the fan and sealing off the opening while doing that work. Also, the very best way to reduce your attic temperatures is to install a white or light colored roof. This is one of the reasons that metal roofs are making a big surge into residential construction. There are many attractive light colored roofs available as opposed to less attractive white shingles (don't see too many of those!) Good luck.