ABS to copper tub drain

Discussion in 'Plumbing Forum, Professional & DIY Advice, Tips & ' started by corkercoon, Feb 19, 2008.

  1. corkercoon

    corkercoon New Member

    Messages:
    7
    Hi there,

    I am in the midst of replacing a standard bathtub/ shower, and had a question about the ABS drain and overflow connector kit I purchased to the copper (I believe) drain pipe. I explained the situation to a local big box store, and they gave me a compression fitting to connect the 1 1/2 inch ABS to the existing pipe. The next day while checking to see how everying thing would go together, it seems the drain pipe is smaller than 1 1/2.
    Measuring the pipe it seems to be just shy of 1 1/2, but even if the opening was 1 1/2 the compression fitting seems to accomodate for the thickness of the ABS pipe and I do not think it would tighten enough to be a reliable way to connect to the copper.
    Should I look to get a copper fitting that will increase the diameter of the copper pipe to accomodate the compression fitting? Or is there another option I should pursue.
    I can post a picture if you think it would expain things a little better.
  2. corkercoon

    corkercoon New Member

    Messages:
    7
    I googled my problem and seemed to find the below solution. Do you think this would work?

    "Question: I am remodeling a bathroom. The existing drain pipe is 1 1/2" copper tubing. What is the best way to connect a 1 1/2" PVC to 1 1/2" copper tubing?

    Answer: I would take a 1 1/2" female copper adapter and solder it on the copper pipe. Then I would glue on a 1 1/2" PVC male adapter on the PVC. Connect the two with a compression fitting and you'll have a solid connection."

    Do you think that is the way to go?
  3. krow

    krow Plumber

    Messages:
    906
    Location:
    Ontario, Canada
    I suspect that the big box store gave you a BOW adaptor (some guys may called it something else) It is designed to fit copper pipe. The only reason that It won't fit your set up, you could be trying to attach the bow adaptor to a 11/2 tubular tailpeice (diametre slightly smaller than 11/2 copper)

    If you have access from below, I would use a transition from copper to ABS/PVC fernco or a no hub coupling or an MJ clamp (each state calls them different names, but they do the same thing) . A stailess steel band with a neopreme rubber on the inside of the band
  4. corkercoon

    corkercoon New Member

    Messages:
    7
    The adapter seems to be rubber with two metal bands on each end that can be tightened at each side to complete the connection. I do have access from my crawlspace below. I guess the main reason I do not believe the fitting would work is that the total diameter between an 1 1/2 copper to 1 1/2 ABS is quite different due to the thickness of the pipe.
  5. krow

    krow Plumber

    Messages:
    906
    Location:
    Ontario, Canada
    If you use a 1-1/2 x 1-1/4 fernco, it will do the job. The 1-1/4 side will fit the 1-1/2 copper side

    [​IMG]
    Last edited by a moderator: Sep 24, 2009
  6. krow

    krow Plumber

    Messages:
    906
    Location:
    Ontario, Canada
    Speak with the salesman to give you the correct sizes that you need.
    This is what it looks like. You will notice that one side has a thicker neopreme (copper side) than the other

    Attached Files:

  7. Gary Swart

    Gary Swart In the Trades

    Messages:
    7,341
    Location:
    Yakima WA
    Technically, this is not a Fernco coupler. A Fernco as all neoprene with clamps on each end. They are not allowed above ground. What is pictured is a banded coupler which is good for above ground and inside work. Reason is stability.
  8. krow

    krow Plumber

    Messages:
    906
    Location:
    Ontario, Canada
    Technically, what you consider a "no hub coupling" we consider it as "MJ coupling" (mechanical joint coupling)
  9. corkercoon

    corkercoon New Member

    Messages:
    7
    So the one I had was 1 1/2 by 1 1/2, and looked like the image below. Is this the one I should go with but in 1 1/2 by 1 1/4 or something that has the all metal casing in the picture posted above. Just got a bit confused with some of the dialog going back and forth.

    Below is an illegal coupling.
    They tend to sag over time, cutting off the flow.

    Attached Files:

    Last edited by a moderator: Feb 20, 2008
  10. krow

    krow Plumber

    Messages:
    906
    Location:
    Ontario, Canada
    The same manufacturer that makes the image that you are showing me, makes a reducing coupling 11/2 x11/4. The 11/4 side will fit the 11/2 copper pipe nicely
  11. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    21,948
    Location:
    New England
    Unless the coupling is underground, and can be supported by the backfill to keep it in place, you MUST use the one with the metal band around it to keep the pipes aligned if you want it to pass code. They're also thinner, and would fit easier in a wall if it was going there.
  12. krow

    krow Plumber

    Messages:
    906
    Location:
    Ontario, Canada
    How much weight can you expect to be pressing on that fernco coupling above ground?
  13. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    26,535
    Location:
    Cave Creek, Arizona
    coupling

    How much weight can you expect to be pressing on that fernco coupling above ground?

    That is only part of the equation. Part of the rest of it is lateral stability. And do not confuse requlations/requirements with practicality.
  14. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    21,948
    Location:
    New England
    It's not unusual to end up with a little torque on a pipe that eventually causes the pipes to no longer line up. If you strap each end near the coupling (which doesn't happen all that often), it shouldn't be a big deal, but...
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