Replies

1. 
   Andy_Engel_ | Oct 04, 2001 06:26pm | #1

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   Paul, why not build an open-topped plywood box around the fan and blow the insulation up to this box? As long as the box was, I don't know, 6 in. or 1 ft. above the insulation, I don't see how you'd have a problem. Maybe you could even hinge a weatherstripped and insulated lid onto the box, and arrange a rope and pulley system to open it in the spring and close it in the winter. I'd bet that stopping the airflow thatlikely passes around the fan louvres in the winter will save as much energy as adding several inches of insulation to the attic.

   Andy

1. 
   eamgjw_ | Oct 09, 2001 08:30pm | #2

   *That is exactly what I have been thinking of doing, re the hinged door. The whole-house fan has got to be a tremendous energy leak. I have loose-fill fiberglass insulation, and using the fan causes so much turbulence that it tends to rearrange the loose-fill insulation. I have built cardboard baffles in a box shape around the fan frame about 2' high, but still causes problems further away. I may replace the loose with batts.G.Morrison

1. 
   Crusty_ | Oct 13, 2001 07:02am | #3

   *Blown in cellulose is now called "stabilized" -- it's the same as they use to wet spray into your walls (new construction). It has a binder that is activated with a light mist of water. It should stay in place fairly well.I'm building a house now, will have an attic fan, and will have cellulose in the ceilings -- and I hadn't thought of this problem until now.Thinking out loud, what comes to mind, is to put some landscaping fabric over the cellulose near the fan and tack it to the fan "box". It's cheap, will hold the cellulose in place, and will not act as a 2nd vapor barrier.I love whole house fans, but they're noisy, and drafty in the winter. What I'm doing is building an inlet plenum that will get the fan up about 3' higher than normal (this will make it quieter). This plenum will be lined with acoustic foam ("egg crate foam") which will trap the sound. There will be a set of hinged doors below the fan that (as Andy said) will be opened with a pulley arrangement. The doors will overlap in the middle, and will be lined with 2" polyiso foam board, and will have a weather strip around the bottom side. They should seal completely. The fan will also be mounted with a piano hinge -- to get into the attic, you remove the louver, open the doors, and push the fan out of the way (saved having to put in an access door as we have no storage up there).

1. 
   eamgjw_ | Oct 15, 2001 07:49pm | #4

   *Sounds like a good plan. My insulation is pink fiberglass loose chips, about 12". I have thought about a door, but above the fan, not below, and I want it perfectly counterweighted so that the force of the fan opens it, and when the fan is off it will fall shut. I also may remove and remount the fan on some kind of rubber mounts, maybe muffler hangers, so the noise and vibration cannot use the sheetrock ceiling as a sounding board.G.Morrison

1. 
   Crusty_ | Oct 22, 2001 02:48am | #5

   *I won't have the headroom above the fan I thought I would, so your idea of counterweighted doors above the fan intrigues me. Will work on that idea. From my vibration work, I can tell you that rubber isolators must be very, very "soft" to work -- hard rubber just won't work.

2. 
   Paul_ferrari | Oct 22, 2001 02:48am | #6

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   I am planning to add some more insulation to my attic. Can a blown-in insulation be used with a whole house fan? I was thinking of putting a 3-4 foot area of fiberglass batts around the fan to keep the loose insulation away from it.

   Thanks - Paul