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Thread: venting

  1. #1
    DIY Member idoc4u's Avatar
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    Default venting

    I have a roughed in basement bath. The toilet, shower and lav are wet vented. I would like to add a vent off of the toilet (not the riser), and a separate one off of the shower, bring those vent pipes up and T them into a cross PVC that ties into my future vent.

    I believe this would allow for a more efficient and effective system. Does this make sense vs the existing set-up where the toilet, shower and lav all use the same vent (all are within 10ft of the main stack).

    idoc

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    Last edited by Terry; 05-24-2010 at 03:26 PM.

  2. #2
    Journeyman/Inspector Inspektor Ludwig's Avatar
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    Whom ever installed the wet vent, if it was done correctly, was a pretty good plumber I imagine. Wet vents are tricky and the code language is confusing to some. But for those who can figure it out, it provides a drainage system that uses less pipe and less fittings and therefore has less chance of leaking. Are you having problems with any of the fixtures? The system you have is as efficient as you can get and should work great. The added bonus of wet venting a lav, shower and toilet into one stack is that it provides an extra "scrubbing" in the pipes and helps keep them clean. The only time you'd ever maybe have an issue is if someone is taking a shower and running the lav and flushing the toilet at the same time. I'd stick to what you have instead of trying to change.

  3. #3
    DIY Member idoc4u's Avatar
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    Default To: Inspektor

    Inspektor,

    I am going to finish the basement. I need to move the drain pipes for the shower and toilet to some degree and am currently breaking the concrete.

    There are no fixtures, yet.

    However, I am concerned about aspiration and or inefficient venting without the toilet, shower, and lav all having their own dry vents.

    The wet vent is set-up so that the toilet and shower junction at a "y" and that line connects with the lav drain and then that runs to a back water valve. The main stack drains to the back water valve and then out to the street.

    In essence, the only venting for the toilet, shower and lav occurs via the 2" vent coming off of the lav DWV, other than the main stack.

    Wouldn't adding dry vents to the shower and toilet assist in the venting? This way the shower and toilet would still be connected to the lav DWV via a wet vent, but the individual fixtures would also have dry vents.

    Is there any advantage or disadvantage to what I've described, assuming it is understandable?

    Thanks again.........idoc

  4. #4
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    Default

    Toilets don't need a vent (where have I heard this before?)
    They are a self vented, s trapped fixture. The IPC only says that there has to be a vent somewhere. The distance from toilet to vent is unlimited.

  5. #5
    Journeyman/Inspector Inspektor Ludwig's Avatar
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    Ok,
    let me see if I have this correct. Is the wet vent a vertical wet vent or a horizontal wet vent? Do you know what plumbing code you're under? UPC or IPC? Wet venting is great way to save pipe and fittings and still provide a code compliant and highly functional system. What you're proposing is fine but if you don't need to then why bother. There is no aspiration or other problems that you may associate with wet venting. The idea of wet venting came about with the understanding that not all fixtures would be used at the same time in one bathroom so I believe that this method is preferable to plumbers because it provides a code approved system without the extra holes through the studs, extra pipe and fittings that may leak and it takes less time. I try to wet vent where ever I can. Maybe some other plumbers could comment on what they think of a wet vent just to give you an idea.
    Last edited by Inspektor Ludwig; 11-21-2009 at 11:14 AM.

  6. #6
    DIY Member idoc4u's Avatar
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    Default Inspektor

    Thanks for the replys.

    It is a horizontal wet vent under the basement slab. I don't know if code is UPC or IPC.

    2" Shower drain and 3" toilet drain meet at a wye. The PVC continues to the 2" lav drain then on to the backwater valve and out. The main stack connects to the backwater valve via a branch under the slab.

    e.g. (view looking down)

    O (main stack) O (shower) O (toilet)
    l l /
    l l /
    l l /
    l l /
    l l /
    l l/
    l /
    l /
    l /
    O (back water)-----------------------O (lav)

    Thanks again for your input and for looking at my technical drawing..idoc

    Plumbing Codes New Jersey
    Last edited by Terry; 11-21-2009 at 10:57 AM.

  7. #7
    DIY Member idoc4u's Avatar
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    Default image didn't come out

    sorry, the image was supposed to depict the shower and toilet connecting at a wye and then on to the lav and then to the backwater valve.......idoc

  8. #8
    Journeyman/Inspector Inspektor Ludwig's Avatar
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    Hmmm, horizontal wet venting is new to the UPC. I believe the section of the code was taken directly from the IPC. It's an attempt to bring the two codes together but that's another thread. We've asked IAPMO who publishes the UPC to better define horizontal wet venting. From the official IAPMO interp. dept. I understand it to be like this;


    The code clearly stated that the toilet had to be the furthest most downstream fixture. If the system you describe is like this than it is approved by the plumbing code I use. Although I have to say I have never installed anything on a horizontal wet vent so I can't say weather or not you would have problems. Maybe a plumber who's more familiar with the IPC and horizontal wet venting could offer up some advice. If it were me I would add conventional vents. The UPC and IPC are in conflict with certain parts of the plumbing code.......but then again that's for another thread I suppose. Good luck! Oh crud, my drawing isn't turning out right! I had to delete my drawing, anyway the lav should be the uppermost fixture with a vertical vent off the top in 2" then it goes to horz. and continues 2" then when the shower ties in it should increase to 3" then further down the main the toilet should tie in. All horizontal tie ins should be invert to invert wyes.
    Last edited by Inspektor Ludwig; 11-21-2009 at 02:02 PM.

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    Default

    IPC does not care what order the fixtures enter the wet vent.

  10. #10
    Moderator & Master Plumber hj's Avatar
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    Default vents

    If the existing system is properly vented, wet vents or not, then adding any venting would be useless as far as improving the operation of the plumbing. BUT, how you describe the system and how it is acutally installed may be two different things so a picture, not a bunch of equal signs, would be beneficial to tell what, if anything, has to be done.

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