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Plastic overflow as prv discharge from unvented water heater?

Discussion in 'Plumbing and Central Heating' started by neiloneil, 12 Feb 2018.

  1. neiloneil

    neiloneil

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    I have fitted a ariston 15litre unvented water heater in an airing cupboard. A shower feed is situated fairly close to the unit, so I am opting to use the full range of expansion controls. Pressure reducing valve, Non return valve, expansion vessel, pressure relief valve, and tundish.
    What I want to know is; Is it absolutely necessary for the prv to discharge through copper pipe?
    The plastic overflow that is existing drops 1 meter straight down, then a shallow fall for another 2 meters where it connects to the kitchen waste outlet pipe The fitting guide says this pipe should be metal, but its going to be a problem getting a new pipe back to the kitchen or to an outside wall.
     
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  3. Good question but what does the ariston supplied literature say,ave a chat with them.

    Every installation is different o_O
     
  4. John D v2.0

    John D v2.0

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    Yes, plastic melts easily, the water could be super heated water/steam under pressure, need hard metal piping run to a fall into a gulley or somewhere at low level outside.
     
  5. SandyLyon

    SandyLyon

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    Metal for a reason.
     
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  7. FiremanT

    FiremanT

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    Not saying you can use plastics, but it won't be under pressure after the tundish
     
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  8. John D v2.0

    John D v2.0

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    Didn't spot the tundish, thanks
     
  9. neiloneil

    neiloneil

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    Thanks for your comments. Because of a lack of route options for getting a 22mm copper pipe to an outside wall, I am now just considering getting a like for like replacement of a direct hot water cylinder and immersion heater. As it does not require a vent pipe, I can use the existing pipework.
     
  10. neiloneil

    neiloneil

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    Update..
    I have returned the Ariston 15 litre water heater, and I am now shopping for a direct Fortic cylinder, as it has its own head tank , so venting or discharge is not an issue. I am thinking of an economy 7 type, as I only need the immersion element near the top, otherwise i will be heating up 100 + litres just for kitchen sink and hand basin. Can you suggest any other alternatives please?
     
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