how to meet the 3ft away from any opening requirement?

Discussion in 'HVAC Heating & Cooling' started by lmei007, Mar 24, 2013.

  1. lmei007

    lmei007 New Member

    Messages:
    154
    Location:
    Maryland
    My basement bathroom needs a fan. There is a window in the middle of its exterior wall. please refer to the photo. There is no way to make the duct outlet "3ft away from any openings of this house" if the duct goes forward and terminates on the exterior siding.

    The left of the bathroom is stair. So we cannot go left and then go forward. On the right side there are many drain pipes. It is almost impossible to go right and then turn forward. BTW, the height of the joist is about 9". It seems drill a 4" hole is not a valid option.

    Goes backward is possible and there is an existing exit outlet for old dryer which was moved to other place. But there is about 30' distance from the bathroom to that outlet.

    Just wondering is it possible to satisfy that 3ft requirement with the run outside the siding? For example let the duct turn up outside the wall and run 3ft. But how about louvers or damper? Damper may be necessary and louvers can be replaces with screen I think.

    3 yrs ago the plumber installed a new gas boiler for us in the basement. The exhaust and fresh air PVC pipe both run up about 3 ft outside the building. Both have a "TEE" at the end. Do you think it is a valid option to borrow the same idea to bathroom fan exhaust?

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  2. lmei007

    lmei007 New Member

    Messages:
    154
    Location:
    Maryland
    Got a code book from library and found out there is no such 3ft requirement for bath fan. It is for dryer exhaust.
    Last edited by a moderator: Mar 26, 2013
  3. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    21,832
    Location:
    New England
    You do not want the outlet of anything near the inlet to your boiler. Some of the exhaust components of say a dryer could have lint and maybe some fumes from the perfumes in detergents or softeners, or worse, bleach. Likewise for the bathroom vent - it could have things like hair spray, and who knows what else. These things can get sucked into the boiler's inlet and degrade the burner and exhaust components. You don't want the exhaust to be near an opening door or window, either, but that's more of a olfactory situation than safety. If height is an issue, you can convert a round duct to a square or rectangular one with a lower cross section. Also, the instructions will say how far the fan is designed to exhaust. You may want to find one that can exhaust further if that's better overall.

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