Powerful exhaust fan for in-wall use?

Discussion in 'Plumbing Forum, Professional & DIY Advice' started by miamicanes, Jun 3, 2009.

  1. miamicanes

    miamicanes New Member

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    Computer penetration tester & software engineer
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    Pembroke Pines, FL
    Can anybody recommend any exhaust fans that are powerful (100+cfm), narrow enough to fit inside a standard wall (~4" if you count the cavity and cut-through drywall on one side), relatively quiet (within the limits of physics, of course), and most importantly -- designed so that it's more or less physically impossible for it to blow hot, steamy air into the wall cavity should the duct itself ever become blocked?

    The last requirement seems important to me right now, because part of my bathroom's rampant mold problem (I'm gutting it to the studs & concrete) is due to the fact that at some point over the past 20 years, the exhaust duct became blocked... and worse, the cheap fan installed by the builder had gaps in the body & basically blew that hot, steamy air into the wall cavity itself. I know, because the drywall around the fan actually has more mold than the drywall behind the *shower*.

    Home Depot & Lowes obviously have fans, but it looks like all of their good ones are intended for ceiling mount (too thick for the wall), and I really don't want to go to all this trouble only to settle for a fan that's as low-quality as the piece of junk the original builder put there... as I've discovered, it's next to impossible to actually replace and upgrade a fan down the line without tearing apart the wall, so this is my one chance in 20 years to doit right.

    I'm sure that somewhere in Japan or Europe, there HAS to be a company selling fans with thick plastic bodies (won't rust, can be molded airtight) and powerful, deeply-scooped blowers with linear induction motors whose only real noise comes from the hurricane-force winds being sucked through it... but I haven't found any yet & could definitely use some suggestions for where to look :)

    As for why I can't go in the ceiling or make the wall thicker... the ceiling is a suspended concrete slab with 3/4" furring strip and drywall; the wall is next to the toilet, and already closer than I'd really like for it to be (my knee usually touches the wall during use). A dropped ceiling wouldn't really be practical, because the height in there is ALREADY reduced to ~7'6" by the floor (another suspended slab, formed 6" thicker in the bathroom to give the builder room to embed the pipes... and make it cost-prohibitive to even THINK about moving any of them).
     
    Last edited: Jun 3, 2009
  2. SteveW

    SteveW DIY Senior Member

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    Omaha, NE
    Have you checked out Panasonic? I put one of their fans in my master bath a few years ago because I wanted a quiet, powerful fan that would mount vertically - and at that time they had such a unit. Don't know if they still do but worth checking out.
     
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  4. BimmerRacer

    BimmerRacer Member

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  5. Thatguy

    Thatguy Homeowner

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    Just don't steal Combustion Air from gas-burning appliances.
     
  6. SteveW

    SteveW DIY Senior Member

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    They used to - maybe not anymore.
     
  7. 99k

    99k Radon Contractor and Water Treatment

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    What is above this concrete suspended ceiling? Do you have a basement below the bathroom?
     
  8. doc5md

    doc5md New Member

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    Pennsylvania
    I'm not really sure I understand exactly what you are looking for, but have you looked at Fantech?
    www.fantech.com
    They have all sorts of fan products including those in which the motor is mounted in line, but now necessarily at the opening to the room. moight be worth a look.
    Quinn
     
  9. miamicanes

    miamicanes New Member

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    Pembroke Pines, FL
    Well, to give a little more insight, here's an illustration of the bathroom's layout.

    My house is technically a single-family home, but both side walls are in direct contact with the neighbors' side walls. According to my neighbor, the developer found a zoning loophole that enabled him to build single-family homes to higher density than townhomes, and exploited it by literally separating them with a sheet of Tyvek embedded in the concrete and violently abusing the legal definition of "detached single-family home". It's also the reason why the roof is a concrete slab: it didn't need eaves (which would have triggered additional zoning requirements that would have made the developer's stunt impossible to pull off).

    Anyway, that's why I can't vent through the side wall, and why the roof is concrete. I'm not really sure why the second floor's floor is also a suspended slab, but I'm guessing that it didn't add much to the cost since the builder already had the crews and equipment in place to do the roofs, and probably doubled his purchase of steel pan decking & got him a discount.

    I thought of an inline fan, but since I don't have an attic (ceiling drywall -> 3/4" furring strip -> steel pan -> ~6" concrete -> built-up roof), the only place I could really put it is in the dressing room's vanity. But then, the wet, humid air would enter the duct, descend a few feet to the inline blower on the dressing room side of the wall, then rise back up again to continue out through the existing duct leading outside. I have a hunch a nontrivial amount of water would end up condensing inside the duct and collecting at the low point near the blower.

    I guess I could put the duct itself near the floor (avoiding the need to suck the air down before blowing it back up again), but I'm not sure whether it would be legal, and I'm pretty sure it would be an inefficient place to put it since steam presumably rises.

    Going down isn't really a viable option, either. I'd still have to cut a ~4" hole through the slab (definitely beyond my means... I wasn't even able to drill a 1/4" hole through it for ethernet cable when I tried last year), and THEN it would end up ~15 feet away from the rear exterior wall... with the kitchen and laundry room in between (the fan over the stove isn't vented to the outside... it just blows back through a filter).

    From what I can tell, the main problem is that the only time narrow in-wall exhaust fans are used is when a builder is trying to be cheap. Since it's next to impossible for consumers to meaningfully upgrade their builder-installed exhaust fans without tearing apart the wall, the market for high-end 3.5" deep exhaust fans is basically nonexistent (in the US, at least). Ergo, the only 3.5" fans you can buy (in America) are the cheapest of cheap junk builders buy because there was no cheaper alternative to use instead. What I need to find is the in-wall fan equivalent of a 20" stainless-steel gas range with convection oven and swappable grill module with downdraft exhaust... something that technically exists & people who live in Manhattan or London can buy if cost is no object, but you'll never find on sale at Best Buy ;-)

    Oh, I forgot to mention: locating the intake on the wall between the master bath & utility closet, putting an inline blower in the utility closet, and routing the duct back to the original duct leading to the roof along a route that leads over the door won't work because there isn't enough ceiling height. The top of the door's trim is about 1" from the drywall, and there's only 3/4" gap between the ceiling's drywall and steel pan deck for the concrete slab above (remember, the floor is also raised 6" relative to the rest of the second floor).
     

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    Last edited: Jun 4, 2009
  10. 99k

    99k Radon Contractor and Water Treatment

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    Contractor of Radon Reduction, Testing, and Water
    Location:
    Fairfield Co.,Connecticut
    You have few options. What about going through the roof ... hire a core driller to put a 5" hole through the roof and then you put a 4" PVC pipe through the hole, use hydraulic cement to seal it and then roofing tar. I stock radon reduction fans that can move up to 100 to 350 CFM and are rated for outside use. All you would have inside the bathroom is a grill:)
     
  11. jastori

    jastori Member

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    May 2, 2008
    Location:
    Illinois
    Panasonic has a high quality (quiet) 70 CFM wall-mounted fan available on-line for $255 (model FV-08WQ1).

    Broan-Nutone has a cheap ($60) 180 CFM wall-mounted fan (model 509 or 509S) which is much louder.
     
    Last edited: Jun 5, 2009
  12. jch

    jch Member

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    Jan 3, 2006
    Location:
    Victoria, British Columbia, Canada
    Panasonic makes a fan just for this:
    FV-08VS1 Whisper-Value ($123 list; available for only $79 on-line if you hunt around)
    Rated at 80cfm @ 1.4 sones (which is quiet for a 3" ducted fan)
    Energy Star (23 Watts)

    Comes with instructions for mounting vertically within a 2x4 stud wall so no need to worry about premature bearing wear from being mounted in the wrong orientation.

    Fan is only 3-3/4" thick (gives you code-required 1/4" clearance from back wall surface, and aligns flush with 1/2" drywall in front)

    Uses a 3" duct that runs up vertically within the wall.

    Does this help?
     
    Last edited: Jun 5, 2009
  13. miamicanes

    miamicanes New Member

    Joined:
    May 30, 2009
    Occupation:
    Computer penetration tester & software engineer
    Location:
    Pembroke Pines, FL
  14. 99k

    99k Radon Contractor and Water Treatment

    Joined:
    Aug 16, 2008
    Occupation:
    Contractor of Radon Reduction, Testing, and Water
    Location:
    Fairfield Co.,Connecticut
    Not so fast. How long is the ductwork and is it solid pipe or flex ... this fan is rated at this CFM at only .1" of water column lift (that is terrible).
     
  15. miamicanes

    miamicanes New Member

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    May 30, 2009
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    Computer penetration tester & software engineer
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    It's semi-rigid metal... the kind with ridges and can bend like a straw, but isn't like a metal-plastic dryer vent.

    I'm guessing it's around 3-4 feet long (the duct is ~15 inches down from the ceiling, which is ~15 inches down from the roof surface above.To be honest, I'm not really sure. It goes straight up, and I can't think of any real reason why it would be much taller, but I've only been up on the roof once and don't really remember. The back yard is walled in and topped with a screened enclosure, so the only way I can get on the roof is from the front... but the front has a big wood pergola, so the smallest extension ladder long enough to reach the roof (while nevertheless clearing the front edge of the pergola) is ~30 feet.

    I'm actually going to go measure tomorrow morning to see whether a 22' Werner multi-ladder from Lowe's might do the trick, instead (they're on sale for $149, down from $209). If it can be fully extended, then latched at a point somewhere around 135-150 degrees (vs straight at 180 degrees), I *might* be able to buy one and use it to get up on the roof (with the lower half nearly vertical between the ground and pergola top, then the top half angled in towards the roof itself. in ASCII-art terms:

    -\
    #|
    vs
    -\
    #.\
     
    Last edited: Jun 5, 2009
  16. 99k

    99k Radon Contractor and Water Treatment

    Joined:
    Aug 16, 2008
    Occupation:
    Contractor of Radon Reduction, Testing, and Water
    Location:
    Fairfield Co.,Connecticut
    If you're 3-4 feet long then your friction loss should be limited
     
  17. jch

    jch Member

    Joined:
    Jan 3, 2006
    Location:
    Victoria, British Columbia, Canada
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