Pressure relief pipework

Discussion in 'Plumbing and Central Heating' started by bster, 5 Oct 2006.

  1. bster

    bster

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    Went to a job today and noticed the blow off pipe was copper from boiler then plastic then copper to outside.

    I know that it has to be copper for unvented hot water stores but what about combis?
     
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  3. chrishutt

    chrishutt

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    Normally it would have to be metal throughout, but some C&M Britony boilers were supplied with a short length (300mm) of clear plastic tube which was supposed to be used to link the PRV outlet pipe to the rest of the discharge pipework. Was it a Britony boiler?
     
  4. bster

    bster

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    no, Worcester CDi (or something, it was less than 12months old anyway).
     
  5. ChrisR

    ChrisR

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    I've always thought it had to be copper but is that in a reg somewhere ChrisH? There won't be any pressure on the open-ended pipe so I can't see why plastic isn't OK. Likely to be within the one or two metre radius from the boiler, but hey.

    Coincidentally I hear Baxi are advising that the pipe from a boiler to an open vent should "preferably" be copper. Also, has anyone noticed the description which is with Pulsar's plastic pipes; one type is for H & C water and the other for Vented CH systems.
    The penny may be dropping that it isn't acceptable to use a pipe which may burst before the PRV lets go.
    As mentioned before, Polypipe said they get a complaint every week that a sealed system has burst a plastic pipe.
     
  6. chrishutt

    chrishutt

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    I can't think of one off-hand, other than MIs, but since the PRV discharge could possibly be steam the pipework ought to be able to withstand 100°C for a reasonable time, which I doubt that plastic would.

    When I started fitting combis (early Vaillants) I didn't even realise that they needed PRV discharge pipework (nothing about it in the MIs - I suppose the krauts assumed that we'd be proper Meisters who'd know about these things!) and I just left them to discharge wherever. :oops:
     
  7. div69

    div69

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