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  1. #1
    Join Date
    Jul 2007
    Location
    New Jersey
    Posts
    3,031

    sizing a fart fan

    I have an industrial rooftop fart fan in a mens room. People complain that it doesnt work well and doesnt remove humidity.
    ...Storys been told that when the old supervisor was here years ago, he realized it was undersized but didnt want the hastle of returning it.

    So how would i properly size one of these things?
    “If I have seen further than others, it is by standing upon the shoulders of giants.” ~ Sir Isaac Newton


    I'm learning all the time, the tombstone will be my diploma!!!


    Did you ever stop to think, and forget to start again?

  2. #2
    Join Date
    Dec 2010
    Location
    Down by the river
    Posts
    1,664
    1st you have to get an idea how many fart's per hour, the cfm per fart, devided by the cubic foot of room area, - make up air. you are going to have to take some field measurments 1 day.


    sorry couldn't resist.
    It's hard to stop a Trane. but I have made one helluva living keeping them going.

  3. #3
    Join Date
    Jul 2007
    Location
    Delaware
    Posts
    3,824
    Call Greenheck. They will tell you in about 2 minutes. They love that stuff. Measure the room, get the distance from room to roof, call.

    http://www.greenheck.com/
    Always here

  4. #4
    Join Date
    Dec 2002
    Location
    SouthEast NC ICW & Piedmont Foothills
    Posts
    7,635
    you might want to take the exhaust pipe loose and see what it looks like inside
    It`s better to be silent and thought the fool; than speak and remove all doubt.

  5. #5
    Join Date
    Oct 2009
    Location
    Mukwonago, WI
    Posts
    235
    code around here is a minimum of 75cfm per fixture.

  6. #6
    Join Date
    Jul 2006
    Location
    Anytown USA
    Posts
    2,060
    Quote Originally Posted by Southern Mech View Post
    1st you have to get an idea how many fart's per hour, the cfm per fart, devided by the cubic foot of room area, - make up air. you are going to have to take some field measurments 1 day.


    sorry couldn't resist.

    CFM per fart? Strap a flow hood to someones ass and have them fart?? LOL

  7. #7
    Join Date
    Jun 2011
    Location
    Houston area
    Posts
    1,493
    It depends on where you live. They tend to be larger down here due to the high consumption of enchiladas and refried beans.

    Truth is I never had to size one. Where's genduct when you need him? That guy is an airflow expert.
    The picture in my avatar is of the Houston Ship Channel and was taken from my backyard. I like to sit outside and slap mosquitos while watching countless supertankers, barges and cargo ships of every shape and size carry all sorts of deadly toxins to and fro. It's really beautiful at times.....just don't eat the three eyed fish....

    ¯`·.¸¸ .·´¯`· .¸>÷÷(((°>

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    LMAOSHMSFOAIDMT

  8. #8
    Join Date
    Jul 2007
    Location
    New Jersey
    Posts
    3,031
    I ripped it apart to access the blades and what do you know....1/2'' of dirt surrounded each side of each blade.(no exageration) Theres also damper directly under the fan. Which I dont know why since the fan runs 24-7. The damper didnt have enough flow to open. When i measured the cfm's at first..I was getting an average of 205 in the main bathrooms return. After cleaning and restarting, I got an average of 315. BTW, theres 2 toilets and 2 urinals in there. Its a 1725 rpm motor. 3/4 hp, 120v
    “If I have seen further than others, it is by standing upon the shoulders of giants.” ~ Sir Isaac Newton


    I'm learning all the time, the tombstone will be my diploma!!!


    Did you ever stop to think, and forget to start again?

  9. #9
    Join Date
    Dec 2002
    Location
    SouthEast NC ICW & Piedmont Foothills
    Posts
    7,635
    you got to hand it to this crowd, any subject can be taken to the crapper in a short # of post.
    It`s better to be silent and thought the fool; than speak and remove all doubt.

  10. #10
    Join Date
    Mar 2010
    Location
    Kent, WA.
    Posts
    189
    the damper is a backdraft damper from the sounds of it. is this a belt driven fan, check amp draw and see if you can sheave it up a bit for more air flow.
    Experience
    Is what you get when you didn't get what you wanted.

    A positive attidude will not solve all your problems, but it will annoy enough people to make it worthwhile.

  11. #11
    Join Date
    Apr 2007
    Location
    Pa
    Posts
    758
    Code book states minimum of 75 cfm per fixture (toilet, urinal). If this area is in heavy use, go bigger. Make sure you have makeup air for the bathroom.

  12. #12
    Join Date
    Oct 2009
    Location
    Mukwonago, WI
    Posts
    235
    By code you need 300, I like to size them a little more than design then slow them down, if I ever need to speed it up I can. Is it direct drive or belt? Any room to speed it up?

  13. #13
    Join Date
    Oct 2011
    Location
    NJ
    Posts
    149
    Quote Originally Posted by HvAckid82 View Post
    Code book states minimum of 75 cfm per fixture (toilet, urinal). If this area is in heavy use, go bigger. Make sure you have makeup air for the bathroom.
    That's changed. 2009 IMC says It's 70 cfm per if the room is used frequently, 50 per if usage is lower. The old requirement was 75 per WC or Ur.

    I would go with the higher 70 cfm or more if there have been complaints.

    Also, is there any supply or makeup to the system (louvered door, undercut, supply diffuser/register) you can't take air out if you don't let some in.

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