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Copper to CPVC

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  • Copper to CPVC

    I have to tap into my home's hot water system in the attic in order to join my two different circuits and put them onto one hot water heater. I bet we could get into interesting discussions re how or why to do this, but I'll try to limit the scope of this post to the question at the end of this post. Nonetheless, here is the background of the problem.

    I have decided to use 3/4" CPVC for the long run I have to make between the two copper HW systems. My crawl space is too small to go below the home with the pipes (could be done, but is REAL difficult). And I trust my ability to connect plastic better than my soldering ability so I have chosen CVPC. The home is a remodel that once had only one water heater. Prior owner added a second water heater and separated the house into two hot water zones. One heater has died. My original preference was to just reconnect the two zones down below the house. But I cannot make heads or tails of the rat's nest of remodeled copper connections in the crowded crawl space below. But I can get to the second HW circuit at just one point in the attic as it goes to a half story addition.

    I removed a 20" piece of soldered 3/4" copper from that second hot water system so I could work on it outside the attic and added the 'T' shown below:

    The sequence of copper to CPVC connectors I could find at the local Home Depot is shown also. 3/4" pipe to threaded fitting to CPVC adapter.

    A friend who I consulted told me not to use the threaded connector in the layout because 'it is only to be used on a cold water circuit'. I could not find a CPVC adapter that would solder directly to the 3/4" pipe. The freezes here in Dallas have wiped out lots of the selection of fittings.

    So . . . Can I use the threaded connector on a hot water system or not? If so, should I use teflon tape (white vs yellow).

    Hmmm, just realized I could solder the two threaded pieces together (I guess) to get the equivalent of what I think I wanted to begin with.

    Thank you for reading.

  • #2
    Re: Copper to CPVC

    I would be more concerned with that type M copper than the
    transition. But, I digress...
    As long as you tape and dope the fitting threads, I don't see a
    problem using them on hot water piping. If you do solder it,
    then be sure to unscrew the brass ring and remove the gasket
    and cpvc part of the fitting. I prefer the one piece transition
    fitting that is factory pressed and available in stainless threads.
    Better yet, why not just use a shark bite. One and done.


    • #3
      Re: Copper to CPVC

      Thanks, Jim, for the reply.

      I saw the various sharkbite connectors but did not pay too much attention to them. Just read about them and they seem almost too good to be true.

      I think I will just solder the threaded pieces together for now.

      Would love to digress into the story of how I had to rip out most of my wall because of the dummies built a 75 gal WH into a tiny closet. I'm sure you have similar stories.


      • #4
        Re: Copper to CPVC

        These are the connectors that we use to adapt cpvc to copper


        • #5
          Re: Copper to CPVC

          You shouldn't connect water heaters in parallel like I believe you doing by adding the piece of cpvc between the two now seperate hot water systems. If you pipe water heaters in parallel they should be side by side IMO unless your a math physics wizzard


          • #6
            Re: Copper to CPVC


            I wasn't too clear re. connecting the two systems. One heater is gone and the other is old and will need replacing soon. I don't use much hot water for the whole house. I cannot afford to replace both heaters and thus I am going to connect the two HW circuits to run off the remaining heater and I will replace it later when it dies.

            Yes, I agree about connecting two separate complete systems. That would not make much sense!

   - nice website, nice parts and tools!! Darn minimum orders for parts wouldn't work for me though.