can vent go down few inch?

Discussion in 'Plumbing Forum, Professional & DIY Advice, Tips & ' started by lmei007, Dec 18, 2012.

  1. lmei007

    lmei007 New Member

    Messages:
    154
    Location:
    Maryland
    I need to join a washing machine vent into an existing vertical vent line which is in another room. Because there is a beam, the new washing machine vent will go up, go horizontal and then go down about 5" to connect to the existing vertical vent line. Is that 5" down ok?
  2. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    21,814
    Location:
    New England
    Plumbing in MA without a license can get you in trouble! For a vent to work, it must not have a belly, or low spot just like a drain. Once it is assigned to be a vent, it must slope up all the way to the atmosphere. This is to allow any condensation, rain, snow, etc., to not fill up the low spots because it can drain out. If that line is truly a vent, then you cannot run the WM drain into it, but it can be the vent if you don't have a belly in the run to it, and the distance from the trap is within 5' if it is 2" pipe. Once a vent, always a vent. Once a drain, always a drain. To change the function means you must replace it with a new run so the vent or drain function is not compromised.
  3. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    26,264
    Location:
    Cave Creek, Arizona
    TEchnically, No!, but since it appears that water can drain both ways from the drop location it should work, assuming your description is actually the way it is installed.
  4. lmei007

    lmei007 New Member

    Messages:
    154
    Location:
    Maryland
    Here is my case on the draw. I cannot see any risk of water blocking the vent.

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  5. MACPLUMB 777

    MACPLUMB 777 TROJAN WORLDWIDE SALES RP

    Messages:
    679
    Location:
    Houston, Texas, United States
    Instead of dropping 5" what about going up 10" or 12" and tie in above the joist !

    Which is what plumbers do
  6. cacher_chick

    cacher_chick Test, Don't Guess!

    Messages:
    3,237
    Location:
    Land of Cheese
    We don't know what kind of distances or obstacles you have to deal with. I would rather run the entire horizontal drain below the joist or go up into the the wall of the floor above to tie in. If it is a long distance, I would look for a better/closer place to run a new vertical vent through to the attic and tie in there.
  7. Terry

    Terry Administrator Staff Member

    Messages:
    14,775
    Location:
    Bothell, Washington
    That one makes me smile. We plumbers just hate talking to inspectors, and find it way easier to just do anything to prevent that conversation.
    I can drill holes in walls like nobody's business. I would much rather swiss cheese the home in the right places and be done with it.

    What hj says is right too, It would drain both ways. But if I have an inspector coming out, I'm just drilling the holes. In fact, I'm so well trained in that regard, that I drill em anyway.
  8. dlarrivee

    dlarrivee New Member

    Messages:
    1,172
    Location:
    Canada
    Don't they call that a trap around here?
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