Happy I bought a 100 year old house...(venting question)

Discussion in 'Plumbing Forum, Professional & DIY Advice, Tips & ' started by Piedtyper, Jan 7, 2010.

  1. Piedtyper

    Piedtyper New Member

    Messages:
    4
    Location:
    Edmonton AB
    Finally starting on plumbing and have a question on toilet venting.

    The existing toilet and tub in a main floor bath are both wet vented. The toilet sits right on top of a 4" cast soil pipe and the tub from a black iron pipe to an ABS 90' (no ptrap) then a run of about 3'. (which rises about 4" in the 3' /facepalm) All the tub drain is 2".

    There's no vent for either of these. The cast iron soil pipe runs to the sewer underneath the slab in the basement.

    So...question 1.

    Assuming I replace at least part of the cast iron soil pipe with 3" ABS and 3" abs for the toilet is it ok to continue to wet vent? The run will be very short (less than a foot).

    Next is the tub. Since there's no vent option I'll have to go with a wet vent again. If I go with 2" ABS for the tub and a run of the downward portion to a ptrap then then 2" to the 3" soil pipe is that sufficient?

    Hope this makes sense. I *think* this will all work but not sure on what code says for wet venting.

    Thanks
  2. krow

    krow Plumber

    Messages:
    906
    Location:
    Ontario, Canada
    First you have to define wet venting as you interpret it. Are you sure the toilet and bath tub are not stack vented? Do you know what the difference is?

    If the tub or the toilet are wet vented , you would see a Y fitting on either leg/pipe running up to the basin drain. I'm not sure what you think you are seeing, but your not indicating that you see any such fitting on iether leg

    In homes that are 100+ years old, there would be minimal code compliance, especially if the home was built on a rural road at the time. (farm acreage)
    Last edited: Jan 7, 2010
  3. Piedtyper

    Piedtyper New Member

    Messages:
    4
    Location:
    Edmonton AB
    With further investigation it's not wet vented I don't think. I believe it's more along the lines of "not vented"

    Toilet on top of cast iron (no closet bend) going into sewer pipe under slab. Bathtub drain connected to the cast iron pipe about 12" under the toilet. Nothing else. :(

    Thanks for the quick response btw :)

    -Pied
  4. krow

    krow Plumber

    Messages:
    906
    Location:
    Ontario, Canada
    hmmm........

    Where is your bathroom sink draining?

    Seeing as you are indicating that there is no vent, you will have to rectify the plumbing if you choose to do any work on it. The minute you touch it, you are bound to make it right. Otherwise this question
    would be redundant. And Of course you know you will have to install a p-trap for your tub as well
  5. Piedtyper

    Piedtyper New Member

    Messages:
    4
    Location:
    Edmonton AB
    No sink. The bathroom has a toilet and a tub. I'll take out the tub at some point and make it a normal half bath. This is all to make sure I have a working toilet and tub while I replace the cracked cast iron main stack that's handling waste from the upstairs and is the vent for the house.

    Since the toilet has a trap and yes I'll have a p-trap on the tub that should take care of the sewer gas portion of the equation. The venting I guess I'll have to use an air admittance valve. AAV?

    I believe the top of the AAV needs to be above the flood level of the toilet and tub correct?

    Thanks again.

    -Pied
  6. krow

    krow Plumber

    Messages:
    906
    Location:
    Ontario, Canada
    ooooh wow.

    I'm already not a big fan of AVV's and you should really never use it in toilet applications. Its good for one or 2 fixtures (But not for a toilet vent)

    The toilet will work as it is now. But it will flush. How good?
    well........ thats debatable

    Good luck
  7. Doherty Plumbing

    Doherty Plumbing Journeyman & Gas Fitter

    Messages:
    810
    Location:
    Penticton, BC
    Do you?

    Canadian NPC

    "Stack vent means a vent pipe that connects to the top of a soil-or-waste stack to a vent header our to outside air"

    So you don't "stack vent" something... something is a "stack vent". I have never once in the profession hear someone say "Well we'll just stack vent the toilet!".
  8. Doherty Plumbing

    Doherty Plumbing Journeyman & Gas Fitter

    Messages:
    810
    Location:
    Penticton, BC
    Do you?

    Canadian NPC

    "Stack vent means a vent pipe that connects to the top of a soil-or-waste stack to a vent header our to outside air"

    So you don't "stack vent" something... something is a "stack vent". I have never once in the profession heard someone say "Well we'll just stack vent the toilet!".

    I dont' fully understand what you're saying as I'm trying to picture it in my head. So a picture would be great :D

    But if you're trying to wet vent a toilet you need to make sure aren't trying to use a line a toilet is tied into as a wet vent downstream of that toilet.

    IE if you're draining a toilet into a line upstairs then that line can't be used a wet vent for downstairs. Downstairs would need it's own vent running up to the roof.

    2" for a tub line is overkill but that's ok. The norm is 1.5" because you'll find that the waste and overflow kit you get for the tub will come with 1.5" fittings. Although you could transition to 2" before the trap and this would probably be ok in your code area. You're usually allowed to make the trap 1 size bigger then the fixture outlet pipe if you chose to do that.

    Hope this helps.
  9. krow

    krow Plumber

    Messages:
    906
    Location:
    Ontario, Canada
    Listen here Doherty Plumbing,

    Don't drag me into your politics on this board questioning me. I know exactly what stack venting is. And your not the one I'm explaining to.

    I Interpreted what He said just fine
  10. Piedtyper

    Piedtyper New Member

    Messages:
    4
    Location:
    Edmonton AB
    My limited understanding is that wet vent means there's waste running some distance until it meets up with a junction that is connected to a pipe that eventually runs to the roof.

    Code says how far it can run etc. etc. for the diameter of the pipe.

    This bathroom (tub & toilet) has no vent. Nothing. The toilet sits on top of a cast iron pipe (no closet bend just straight through a neoprene sleeve and a couple hose clamps).

    The bathtub then goes into that same cast iron pipe after a run and a p-trap. No vent at all. Toilet flushes fine. Tub doesn't drain well but I'm pretty sure there's a clog I'll discover as I tear it all out.

    There's no option for connecting on a vent above the fixtures unless I go to the roof and through the second floor. I can't (I don't think) run a waste line across the room in the basement to the "stack" that's about 12' away but that's the closest true vent there is.

    I think my only option is to use an AAV. I could try and isolate it to only vent the tub and rely on the toilet still operating as it has I guess...

    Any other suggestions on options are welcome.

    Thanks for the replies. :)

    -Pied
  11. krow

    krow Plumber

    Messages:
    906
    Location:
    Ontario, Canada
    Piedtyper I understood precisely what you have.

    Just understand that what you are proposing is not code compliant The concept is to try and keep sewer gases out of your home and stay where it belongs (in the sewer pipes) What ever you do will have to be very, very temporary. Please do not take this statement to mean that its OK to do.

    No plumber would advise you or condone anything against codes

    A wet vent , in layman's terms

    A drain that is used to drain a fixture (IE:sink) and also vents another fixture (such as a toilet or a bath/shower) at the same time. The sizing of the wet vent will depend on the fixture you are wet venting . The NPC will have the size of wet vent per fixture. Of course certain specific requirements need to met, as all plumbing does.

    (I hope you understood it. Codes do get confusing sometimes for the average person)
  12. Doherty Plumbing

    Doherty Plumbing Journeyman & Gas Fitter

    Messages:
    810
    Location:
    Penticton, BC
    Use an AAV then. I have used them to vent a bathroom group before and they work just fine. They can be a bit noisy but w/e it's a cheap quick method to vent when you're in a pinch.
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