3" PVC stack into Cast iron cleanout

Discussion in 'Remodel Forum & Blog' started by snelson57, Jan 26, 2005.

  1. snelson57

    snelson57 New Member

    Messages:
    1
    I am adding a full bath into the 2nd floor of a Cape Cod. I have run a new 3" stack over to the existing cleanout in the floor, which is 4" cast iron. The cleanout has a 3 1/2" brass plug. Is there an adaptor available to bring me from 3" PVC to thread into a 3 1/2" cast iron fitting? What are my options?
    Thank you.
  2. Plumber2000

    Plumber2000 Plumber

    Messages:
    196
    Location:
    Eugene, Oregon
    Not that I'm aware of. 3-1/2" is an odd thread size. Sorry.
  3. Phatbrain

    Phatbrain New Member

    Messages:
    17
    Location:
    Pacific North Wet
    Pipe Sizes - now and then

    Greetings Snelson,


    I’m curious about your 3.5†pipe. A common mistake with pipe is trying to measure it with a tape measure. If your clean-out plug measures 3.5â€, then what you have is a 3 inch pipe.

    It’s kinda like trying to find 2 inches or 4 inches on a 2 x 4 stud. A long time ago (in a land far – far a way…) when steel chemistry was crappy, the pipe walls were thicker. So, an I 1/2 pipe I.D. was 1.5â€.

    As steels improved, they were able to make the wall thinner, but to keep the pipe “backwards compatible†with existing fittings, the pipe O.D. was kept the same as before.

    Pipe
    Size:

    1/2" =0.840" o.d.
    3/4" =1.050" o.d.
    1" =1.315" o.d.

    1 1/4" =1.660" o.d.
    1 1/2" =1.900" o.d.
    2" =2.375" o.d.

    2 1/2†=2.875" o.d.
    3" =3.500" o.d.
    4" =4.500" o.d

    5" =5.563" o.d.
    6" =6.625" o.d.
    8" =8.625" o.d.

    10" =10.750" o.d.
    12 =12.750" o.d


    Phat
  4. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    26,176
    Location:
    Cave Creek, Arizona
    co

    About the only common bushing you will find is a 3 1/2" x 2" one. But the cleanout is not an approved sanitary fitting so you should not connect your drain to it, but should install a proper sanitary tee for the connection and be sure to retain, or provide a new, cleanout in that area.
  5. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    26,176
    Location:
    Cave Creek, Arizona
  6. Phatbrain

    Phatbrain New Member

    Messages:
    17
    Location:
    Pacific North Wet
    Gotch - thanks HJ.

    The confusion on pipe / tubing sizes is one that I battle constantly.

    Phat
  7. macska

    macska New Member

    Messages:
    32
    Why can't I use the cleanout to connect an auxiliary DWV stack if I install a new cleanout into the new stack so that it can be used to reach both?
  8. Kristi

    Kristi Tradesman Plumber

    Messages:
    176
    Location:
    Vancouver, BC
    Macska, I think HJ explained that part already...?
  9. macska

    macska New Member

    Messages:
    32
    Edited: HJ, plumguy and Kristi have kindly begun to address my question on another thread. No need to have two threads on the same issue.
    Last edited: Sep 17, 2005
  10. jimmie

    jimmie New Member

    Messages:
    30
    ummmm

    anyways just to answer your question...they do make a 3 1/2" tp 3" reducing bushing =) it's available in both black, and galvanized.
  11. finnegan

    finnegan New Member

    Messages:
    250
    Location:
    CT
    As Jimmie said, A plumbing supply store should carry the fitting you need. I just bought a black fitting and my store had it in stock. It is not a Home Depot item.
  12. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    26,176
    Location:
    Cave Creek, Arizona
    posting

    Phatbrain, I am curious how you inserted that quote and posted the reply using my "account".
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