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  • PVC pipe melting?

    I do work at this condo complex which has two 2" pumps on it's swimming pool. THe weirdest thing happens. I recently installed new piping with new ball valves and also Jandy check valves both before and after the pumps. Twice since I installed everything, the pvc union nut on the outlet of one pump will deform. There is a short piece of 2" pvc between that and the check valve which also deforms(bulges outward) and then pops out of the nut. It looks like it's melted....but it could be presssure related also. Does anyone have any ideas or has anyone encountered this before? Thanks.

  • #2
    Re: PVC pipe melting?

    Some pictures of the piping would help identify what may be the cause.

    A couple of questions:

    Why a check valve before and after the pump?

    Is the pipe and fittings rated for the fluid temperature and pressure?

    Are the valves in fully open position?

    Are they full port valves?

    Are you using the proper glue/primer?

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    • #3
      Re: PVC pipe melting?

      Last time I saw something like that it was caused by the heater being plumbed wrong. Any chance the heater flows through that pump?

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      • #4
        Re: PVC pipe melting?

        Originally posted by vette850 View Post
        I do work at this condo complex which has two 2" pumps on it's swimming pool. THe weirdest thing happens. I recently installed new piping with new ball valves and also Jandy check valves both before and after the pumps. Twice since I installed everything, the pvc union nut on the outlet of one pump will deform. There is a short piece of 2" pvc between that and the check valve which also deforms(bulges outward) and then pops out of the nut. It looks like it's melted....but it could be presssure related also. Does anyone have any ideas or has anyone encountered this before? Thanks.



        WHat kind of heater is it? I have put in a Ton of these and it is req. by the manu. To put at least 11'' Of CPVC or Stainless steel nipples

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        • #5
          Re: PVC pipe melting?

          It is a propane heater....however it is located over 15 ft away from the pumps. I don't do a lot of pumps, but I was thinking that it didn't need check valves both before and after so I am considering removing them from the outlet side of the pumps.

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          • #6
            I

            I have encountered this problem several times. I have found that the pump looses its prime and the water left in the pump get so hot it melts the fitting and pipe about 8'' out. If you use cpvc it should take the heat. You also should find out if something is plugging up the skimmer or floor intake. Good luck

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            • #7
              Re: PVC pipe melting?

              I've pulled out submersible pumps where PVC was used to connect to the pump whereby it warped the first foot of the pipe where the MIP threaded into the pump head.

              Heat is to blame.
              Northern Kentucky Plumbers Twitter Feed | Plumbing Videos

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              • #8
                Re: PVC pipe melting?

                When ever you connect into a pump you should use sch 80 pvc. Pumps have a tendency to get hot and sch40 cannot handle the heat. Just install a 4-6" long sch80 nipple. Problem solved.

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                • #9
                  Re: PVC pipe melting?

                  Originally posted by Watersurgeon View Post
                  When ever you connect into a pump you should use sch 80 pvc. Pumps have a tendency to get hot and sch40 cannot handle the heat. Just install a 4-6" long sch80 nipple. Problem solved.

                  I went one step better;


                  Type M copper (pressure, not dwv) and a 1.5" to 1.25" copper MIP and that's lifetime piping.
                  Northern Kentucky Plumbers Twitter Feed | Plumbing Videos

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                  • #10
                    Re: PVC pipe melting?

                    Originally posted by vette850 View Post
                    It is a propane heater....however it is located over 15 ft away from the pumps. I don't do a lot of pumps, but I was thinking that it didn't need check valves both before and after so I am considering removing them from the outlet side of the pumps.

                    pumps don't mind pushing, but they don't like to pull. I'd say all other things being equal, you are better off with the checks on the outlet side so the restriction is there, not on the inlet.
                    This is my reminder to myself that no good will ever come from discussing politics or religion with anyone, ever.

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