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larrens

Starting Member

1

Monday, December 21st 2015, 9:48pm

PVC connections to metal tap - advice needed please

I am in the process of installing a sprinkler system in my small
garden. I cannot connect to the mains water supply because it is on the other
side of the house.


Rather, I am connecting the solenoid to the outside tap via
rigid poly riser pipe. I will leave the tap in the open position.





I have 2 questions:


  1. PVC to PVC - When I connect the PVC poly riser to the PVC dual-check valve which
    in turn is connected by a PVC elbow to the solenoid, I understand I should never
    use Teflon tape on PVC. Do I need any thread seal glue or cement or should the
    PVC remain leak-proof if I “hand tighten + 1 turn”? Some forums say I don’t need anything but since the
    tap will remain open with pressure in this pipe leading to the solenoid I wanted
    to get advice.
  2. Metal to PVC – the tap head has a 2-way metal manifold (it is not brass). The
    manifold has a male outlet and I will be screwing in the female end of the rigid
    PVC poly riser. I want to ensure there are no leaks from here from the water pressure
    when the solenoid is closed and the tap is open. The male head on the manifold has approx. 1cm of
    thread, while the female end of the riser has much more than 1cm of thread. Again,
    I assume here I need Teflon tape on the metal manifold head, but should I also use
    a thread seal glue or cement here given the short metal manifold thread?




Thanks

Wet_Boots

Supreme Member

Posts: 5,133

Location: Metro NYC

2

Wednesday, December 23rd 2015, 10:48am

You should do a little better than to have a wye connector on a hose bib supplying your project. More appropriate would be an garden-hose-to-pipe-thread adapter, followed by a threaded tee. One leg of the tee supplies a backflow preventer (yes you need code-approved plumbing) and the other leg supplies a hose bib.

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