bathroom ceiling fan

Discussion in 'Remodel Forum & Blog' started by muzz, Nov 6, 2007.

  1. muzz

    muzz New Member

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    21
    I have come to a standstill of sorts in my bath remodel, hoping the picture helps to explain the situation. We have decided on a bathroom fan for our project, now the problem is how to run it to the outside. This is a 2 story house, going up won't work, there is a bathroom right above. I thought about doing a wall fan, but not quite what we want. We would like to position the fan in the center of the room, and the shortest run to the outside would be across the ceiling joists. Would it be possible to header these joists off where the red lines are, to the rim joist with joist hangers. I am concerned about weakening the floor because there is already a header put in for the upstairs shower. Would this be chopping up the framing too much, or would it be strong enough? I thought of another option; running the ducting with the floor joists thru the ceiling of another room (suspended ceiling, so not too much of a problem). Its about a 20 foot run, and terminates at the deck ledger board on the second floor. (The duct would then be right under the deck) Is this kosher do you think?

    Attached Files:

  2. leejosepho

    leejosepho DIY scratch-pad engineer

    Yes, that would not be a good idea.

    If those joists are 2x10s, I would add some 3/4" plywood plates (9x48) on each side then use a 4-1/4" hole saw at the vertical centers of those joists and run your duct between your red lines.
  3. muzz

    muzz New Member

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    unfortunately the joists are only 2x8, so I guess the only way to go is thru the next room and out the back of the house. Do you think there would be a problem with it terminating below the deck?
  4. muzz

    muzz New Member

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    21
    almost forgot, planning on buying a panasonic fan, any recommendations where to buy from? Thinking about buying from Westside Wholesale on the net, not a lot of options for buying where I live.
    Last edited by a moderator: May 18, 2010
  5. leejosepho

    leejosepho DIY scratch-pad engineer

    "Outside is outside", I would say. But, others here might know more about that kind of thing.
  6. AZ Contractor

    AZ Contractor In the Trades

    Messages:
    90
    Location:
    Phoenix, AZ
    Do not attempt to cut into the framing members unless you plan on hiring a structural engineer first so he can design it for you.
  7. frenchie

    frenchie Jack of all trades

    Don't chop up those joists - you're right, they've already been cut up enough. And how would you attach the header with that pipe in the way?

    20 feet's a bit far. I think you'd need a booster fan... and then you'll still have condensation issues to reckon with.

    I'd say, pitch it 1/4 per foot to the outside, so any condensation drains out... but over 20'... have you got 5" of play? Depends on how low the suspended ceiling is, I suppose.

    Any way to go up, inside a wall of the bathroom above?
  8. muzz

    muzz New Member

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    Well, at least I know that I can't go out thru the bathroom wall, the 20 foot run looks like the only option. I am hoping to keep the pipe within the joist cavity for the run, but depends on where the outlet is on the fan itself. I have another 3 inches or so below the joists in the next room, so I have some room if I need it. I am thinking that if I use foil tape on all the joints and secure it to the joists with strapping or something along those lines to keep a pitch to the pipe, I should be ok? There is some option of going up, but hate to consider it really--wouldn't I still have a condensation problem that way?

    Any recommendations where to buy online, I am considering Westside Wholesale; anybody used these guys?
  9. statjunk

    statjunk DIY Senior Member

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    542
    I've purchased from Westside several times. They are a good outfit.

    Consider that you'll likely need a booster fan if you running that far. Booster fans make noise and are annoying. I don't care how quite the package says it is. In addition you can't bury the fan. I believe it has a transformer attached to it so you're going to need an access hole to service it.

    I'd look for another solution.

    Does the room butt an outside wall?

    Tom
  10. muzz

    muzz New Member

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    Yes, the one side where I originally was going to install the duct is the outside wall. I had considered a wall fan, but that isn't working out.

    The bath is 10 x 13, and I had wanted to mount the fan in the center of the room. I am putting a soffit in over the vanity area (which is on the outside wall), and am now considering putting the fan in that over the vanity. I have 11 inches of space between the first joist and the rim joist, so it would be a very short run to the outside. The soffit is only 6 inches lower than the ceiling, I am thinking is not the best, but pretty close?

    I am thinking I should buy a timer for the fan since it won't be at ceiling height to make sure to get rid of the moisture in the room. I found a panasonic fan that has the measurements I need to fit (FV-15VQ3), but haven't decided if that is the one yet, still weighing the options.

    I think this may be the best way to go...
    Thanks for everyones input so far...
  11. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

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    22,154
    Location:
    New England
    While they can be pricey, I've seen hygrometer based switches...you set the humidity level you want, and it will run until it gets below that.
  12. frenchie

    frenchie Jack of all trades

    I wish we had more HVAC guys here - I can't think of a fan you could do this with - but it'd be ideal if there was a way to mount a grille onto the side of the soffit?

    Either way, I think the 19' reduction in run far outweights being 6" below ceiling height.
    Last edited: Nov 9, 2007
  13. leejosepho

    leejosepho DIY scratch-pad engineer

  14. Hube

    Hube New Member

    Messages:
    156
    Location:
    Ontario
    Imo,the circumstances involved would indicate that the best and safest way is to install a WALL fan. Exhaust the air to the outside,and make sure there is a "backdraft" louvre installed to prevent any entry of outside air when the fan is not runnining.

    And fyi, there are also soffit vents on the market that incorporate backdraft shutters. They work great too.
  15. muzz

    muzz New Member

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    I think I have decided that I am going to order the panasonic fan, and a dehumidistat as you guys are recommending. The picture shows where I plan on installing the fan--it will be an extremely short run to the outside; this is the rim joist that is circled. From what I have read about humidistats, it sounds like the setting on it has to be changed as the outdoor temp changes, correct? With this short of a run, would it be a problem using an elbow right after the exhaust flange? I am thinking that I would have to put an elbow up, and then out thru the rim joist.

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  16. leejosepho

    leejosepho DIY scratch-pad engineer

    Not that I know about, but maybe someone else knows better. The dehumidifier next to the sump in my basement remains at the same setting year-round, but it runs more often and longer in the summer when the ambient humidity is higher. I hope to get my bathroom project finished over the next few weeks, and I am assuming the dehumidistat connected to the exhaust fan will do about the same.

    Not that I can see.

    In your picture, that joist does not appear to be sitting on top of the wall. If not, some reinforcement should be added.
  17. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    22,154
    Location:
    New England
    For a humidifier, the better ones come with an outside sensor. That sensor adjusts the relative humidity level the humidifier is attempting to attain in the house so that on a really cold day, it doens't put quite as much moisture in the house so that you don't get condensation on the (probably) cold walls. Also, it automatically shuts off as the temperature outside gets higher. Mine won't let it run if the outside temp is 50F or higher. It works pretty well, and came standard with the AprilAire humidifier I installed. It is optional on others.

    Removing to 50% in the winter might be great, but 50% in the summer might be too much (i.e., not attainable because of local conditions). So, adjusting it to the outside ambient temperature might be useful. If you don't, depending on where it is set, it might never turn off.
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