Copper to PVC/CPVC Transition Question

Discussion in 'Plumbing Forum, Professional & DIY Advice, Tips & ' started by dowop, Jun 14, 2005.

  1. dowop

    dowop New Member

    Messages:
    19
    I see that this has been discussed alot in the past, but my question has to do with the accessability of these connections. When these transitions exist on both the water supply and drainage, do they need to be accessable? In other words can they be inside a wall? I know that the code does not allow for female PVC connectors in any situation.

    Thanks in advance.
  2. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    26,315
    Location:
    Cave Creek, Arizona
    Pvc

    The codes do not allow any female thread plastic adapter because they are all subject to cracking due to the expansion of tightening them. There should not be any PVC inside the house, much less inside the wall, so your question should be academic.
  3. dowop

    dowop New Member

    Messages:
    19
    HJ,

    Not sure I understand your response fully - I can make these connections without using a female PCV/CPVC. I do understand the code in regards to PVC and female connectors. I know for a fact that there can be Copper to CPVC in your house for potable water and as far as I know Copper to PVC is allowed for DWV inside your house (certainly Copper to ABS). Can you elaborate more on this? Hope I did not misunderstand your response.
    Last edited: Jun 14, 2005
  4. RioHyde

    RioHyde Plumber

    Messages:
    339
    Location:
    Cincinnati, Ohio
    For DWV: To make the transition from copper to PVC you need to use a banded coupling/mission coupling. These couplings have the stainless steel band covering the entire "rubber boot" (not the rubber couplings with two hoseclamps). These banded couplings are available in a variety of sizes and transition configurations. For example 3" Copper X 3" Plastic. The copper end will be thicker to accommodate for the smaller outside diameter.

    For Water: You cannot use PVC for water distribution inside the home. You'll need to use copper, CPVC or PEX. To make a transition from copper to CPVC, there are CPVC adapters. These are male adapters that are cemented onto the CPVC and have brass male threads to thread into a copper female adapter.

    Hope this helps and Good luck
  5. dowop

    dowop New Member

    Messages:
    19
    Is this any better then soldering a copper female onto DWV and using a male PVC/ABS to connect to it?

    The real question still remains - are these transitions allowed to be in a wall that is not readily accessable once the 'rock is on the wall. It will be difficult to put an access panel in because it will be behind kitchen base cabinets.

    Thanks!
  6. RioHyde

    RioHyde Plumber

    Messages:
    339
    Location:
    Cincinnati, Ohio
    1) yes it is better. Torque the band down to 60 inch-pounds and you'll not have to worry about it.

    2) yes you can, but if at all possible, I'd put an access panel through the back wall of the cabinet and drywall. I wouldnt worry about the DWV, but the waterlines...well. What I would do is take whatever waterline piping (CPVC or copper) you have existing and continue with the same piping thereby avoiding the transition altogether.
    Last edited: Jun 14, 2005
  7. jrejre

    jrejre New Member

    Messages:
    61
    Location:
    Minnesota
    Rio - don't they call those "No Hub Couplers"?
  8. RioHyde

    RioHyde Plumber

    Messages:
    339
    Location:
    Cincinnati, Ohio
    Here is an example of both the no hub coupling and a proflex coupling. Both of these examples are made by Fernco. Other manufacturers make similar products.

    When installing no hub cast iron, I use the no hub couplings. When making transitions between two different types of piping I use the proflex couplings. Proflex couplings can be used for example to transition between copper and plastic/CI due to one end of the neoprene boot being thicker to accommodate the smaller OD of the copper. If you tried to transition using just a no hub coupling, one end of the NHC would be crushed due to the fact that it isnt designed for a smaller OD pipe. In addition if I did want to transition from CI to plastic using just a no hub band, inspectors around here would make me also use a PVC no hub adapter.

    Attached Files:

    Last edited: Jun 14, 2005
  9. dowop

    dowop New Member

    Messages:
    19
    Great information - thanks to all!
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