I have a whole house fan in my hallway ceiling that works great. I turn it on and open the windows throughout the house and it sucks in cool air.
I just had all the old bat insulation removed and am going to have new insulation installed.
My concern is that when I turn on the fan, it blows air out the eave vents from the attic. A lot of these vents are right above my open windows and I'm sucking attic air and contaminants in through the windows.
Whatever insulation I install, will have particles floating around that could be vented out the eave vents and sucked into the house.
The only insulations that I can come up with that may not do that are sprayed in foam(really expensive) or the foam board.
I suggest you put a HEPA filter with carbon pre-filter in the attic (HEPA filter can out fine particle, and carbon pre-filter can deodorize the stale air), and install "rockwool" insulation. Rockwool is made out of rock. It won't penetrate skin like fiberglass would. Rockwool is also called mineral wool.
The first couple years when I went up in the attic I wore a mask, because of the fiberglass. 40 years ago the hardware store was selling
3M N95 masks. After 5 years I figure the fan must have blown out anything floating and after 10 years, anything I kicked up, but I still wear the mask.
But in your case it might be much harder to wear a mask. Last Saturday night I smelled the forest fires in Canada and put on a KN95 mask and though it never bothered me when I'm out doing errands, it quickly bothered me when I was sitting at my desk.
No, it is not. There are grades made for insulation use and have been modified to go out when the flame source it gone. That is true of both Dow Styrofoam and Expandable Polystyrene.
Does it matter which way batt insulation is installed? Regardless of whether fiberglass insulation is installed in a wall, attic, or crawlspace; the paper facing should always face toward the inside of the home. That's because the paper contains a layer of asphalt adhesive which prevents water vapor from passing through it.
Still not allowed to be un-covered anywhere by Canadian code. Urethane foam or Polyisocyanurate, are safer (but not necessarily SAFE -) I prefer rock-wool anywhere it is a viable option. Fire PROOF, not fire resistant - no offgassing, will not support mold or varmints, does not hold moisture
Slight correction there Ed. Vapor barrier is always on the WARM side
- the high humidity side. In warm climated where heating is not an issue but cooling and "conditioning" (dehumidification) vapor barrier is more usefull on the OUTSIDE
That isn't going to work unless you put those filters on every air opening in the attic. Most are not easily accessible or shaped to accept them, eg soffit vents as he described.
I never thought about a whole house fan and insulation, but he has a valid point.
Your idea is crazy. No air filter can work fast enough to filter the air going out the window. A HEPA filter can remove contaminants in a "confined area".
That OP said "My concern is that when I turn on the fan, it blows air out the eave vents from the attic. A lot of these vents are right above my open windows and I'm sucking attic air and contaminants in through the windows".
The HEPA filter will remove contaminants in the attic, and the carbon pre-filter will remove stale odour in the attic, when the "whole house fan" is not turned on, and the attic is effectively a "confined area".
I can go under the soffit vents outside the house and smell the attic air being pushed out when I turn on the whole house fan.
These vents are right above the windows where I'm sucking in cool air to the house.
I don't want to be breathing this. Not now that there isn't any insulation, or later when I have new insulation installed. I'll probably have blown in fiberglass.
To fix my soffit vent issue, I'll probably remove the fan to the attic and install a whole house fan in a wall somewhere that will vent the air directly outside.
Depending on how many such window there are, if there aren't too many, you might just want to cover the soffits above those windows with a half-sheet of plywood or somethign. I know the 2x6's will be in the way a little but even if the plywood is on top of them, it should make a big diffeence, especially if insulation is filling the 6" up to the soffits.
The air will be expelled through other soffits.
From the living space straight to the outside? FWLIW, I've never heard of a fan like that.
We had a whole-house fan when I was in JHS and HS. It came with the house and so we used it once in a while. Two big problems, It was so loud. They are probably quieter now, with speed controls allowing one to make it run slower. It only worked after it got cool enough outside. On hot days that can be 10 or 11PM -- or later? That meant the house was still hot until 10 or 11 or later, and even after the air was exchanged, everything in the house was still hot, conducting or radiating heat into the room.
When I got this house, I found that much (most?) of the heat on the second floor was coming from the ceiling, from the attic. I put in a roof** fan that has a thermostat and it turns on when the attic starts to get hot, maybe 10 or 11AM, and turns off when the attic is cool enough (maybe 80 or 90F, I use the original setting and I don't remember if they said what it was.) It turns off 8 or 9 PM but on hot days, 11,
12, or even 1AM
**They also have such fans that go in the side of the attic when it has a vertical side.
It made an enormous difference in how hot the bedroom floor was. I moved in in May, didnt' run the AC when I wasn't home, and when I got home in the summer the upstairs was too hot to go upstairs at all. I slept in the basement the first summer. After the fan went in, I only needed AC maybe 10 days a summer.
I also put foam rubber around the trap door to the attic, so the roof fan didn't suck air from the 2nd floor to the attic. It sucks in air from the outside to the attic and then blows out the attic air to the outside. So the attic never gets hotter than the outside air. Without the fan the attic would get 120, 130F and that would heat the actual attic floor, even when covered with fiberglass, and heat the 2nd floor.
So it's not about cooling off the residential area. It never gets that hot to begin with.
ONe year some tree left loads of "cotton" floating in the air and sucking in so much air through the soffits clogged the soffits on the outside with what was like a layer of lint or felt. It peeled right off but I did have to do that, once. It hasn't clogged again.
Also when it was reshingled, I used light brown shingles, which keeps a lot of heat out of the attic in the first place, compared to dark brown. White would work even better but they seem to get noticeably dirty near the chimney.
Do you want this HEPA filter to catch all the incoming air from the whole-house fan, or to keep conaminatns from getting out the soffit above the OP's open window?
Maybe I'm wrong, but I didn't t hink the smell was a real problem for the OP, only a way of his tracking the attic air.
How ofen wiill the HEPA filter have to be cleaned or replaced? It will have to be 24x24" to accept all the output of the fan or won't it restrict the fan's airflow too much. He'd need to build some frame for it.
I should have asked if he has a roof-line vent. They slightly defeat the air-flow of a roof fan, but with soffit vents, they let natural convection keep the attic somewheat cooler than otherwise. I have a full width summit-roof line vent and it wasnt' near enough to keep my attic even only as hot as tthe outside, but they are still recommended and not that hard to install.
The insulation is not a live animal. The harmful micro fine particle will only shed from the outer surface during installation. After a while there will be no more shedding of micro fine particles. The HEPA filter will eventually remove all those micro fine particles in the attic that came off the insulation.
You could put furnace air filters on the windows you open near the attic outlets.
You could cover the insulation with some kind of fire retardant "breathable" (woven) fabric, or even a perforated reflective foil material.
You could just open only windows farther from the outlets.
You could have a fan that blows INTO the house, so the air blows out through the windows. You could even have a filter before that fan to keep out outside dust and forest fire pollution.
You could just test to see if fibers are really in the air being blown out.
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