Burst PVC hot water pipe

Discussion in 'Plumbers' Talk' started by John3000, Nov 8, 2019.

  1. John3000

    John3000 New Member

    Hi, I hope this is of some interest. So far I can't get a sensible reason for the sudden burst. It is very close to a T junction. I could not work the brand as you see in the picture, there are lots of letter K. Then batch number, made in England. The pipe was installed 11 years ago.

    There are 4 main electric cables touching the pipe. But I don't see the heat generated from the current can affect the pipe.

    Attached Files:

  2. Heat

    Heat Screwfix Select

    The “letter K” is actually a mark line | <
    cut off points for exact push fit fitting measurement to next mark line to show fitting full on. :D
    The burst pipe could be due to overheat. Plastic pipe cannot take very high temperatures and the barrier pipe (although designed for heating as well as hot or cold water) will pull apart, balloon and split.
    I think it can only take 82 degrees max.
    Another reason not to use plastic plumbing.
    You need to see if you have an overheat problem.
    I have seen this happening when an oil boiler overheated.
    Edit, - just noticed looking again at photos that it does indeed have 82 degrees on your pipes.
    It is a standard brand and might be Hepworth or Polypipe - I cant be sure as not as user of the stuff
    KIAB likes this.
  3. KIAB

    KIAB Super Member

    Another good reason to stick with good old copper!

    Not all plastic pipe is the same working temperature does vary between the makes, like Speedfit has a maximum working temperature is 92˚C. The products will withstand up to 114˚C intermittently for short periods.

    And high flow temperatures can shorten the life of the plastic pipe.
    Last edited: Nov 8, 2019
    Joe the Plumber and Heat like this.
  4. Heat

    Heat Screwfix Select

    Absolutely! If water did overheat and reach boiling point or go to steam on a copper piped system it would do no damage to the pipes. On plastic it destroys the pipes.
    I have seen the plastic pipes melting at compression joints and blowing off.
    Joe the Plumber, dobbie and KIAB like this.
  5. KIAB

    KIAB Super Member

    Seen that on a combi with blocked heat exchanger if my memory is right, plastic pipes went all mishapen with a few metres of boiler..
    Heat likes this.
  6. KIAB

    KIAB Super Member

    Was the old Acorn ,Bartol pipe.
  7. Jimbo

    Jimbo Screwfix Select

    The burst itself is caused by air and as noted an abnormal temperature. The pressure rating of the pipes decreases rapidly from 20*C up to their max temp.
  8. dobbie

    dobbie Screwfix Select

    Not a fan of plastic pipe and always use copper, however your figures are wrong.
    Speedfit maximum working temperature for hot water is 95 degree C at 6 bar.
    The maximum for heating is 105 degree C at 3 bar for a short term and will malfunction at 114 degrees C.
    Normal working temperature is 65 C water and 82 C heating.
  9. KIAB

    KIAB Super Member


    3 degrees out hot water....:(
  10. The Teach

    The Teach Screwfix Select

    Ahh,ok now what do you want to do looking forward ?

    The photos exclude other parts of the installation,first thought is installer Error . who the fluke installed it ;) you will have a name
  11. John3000

    John3000 New Member

    If the theory of overheating is correct, then it is the boiler's fault. I did hear air bubble sound and boiler bangs. Usually I bleed the radiator asap. But this, I have left it for a few days. Maybe it is the age of the pipes. It no longer can stand a little high temperature anymore. Again, copper won't have this problem. I need to be so careful with the plastic pipes from now on.
  12. MGW

    MGW Screwfix Select

    My Main 7 gas boiler gas valve stuck, and on turn off there was a delay before it switched off, seems there is a non return valve on the cold water supply, and the pressure release valve had never been fitted, it blew off a sweated copper joint, some thing had to go, as no safety valve.

    So it makes no difference copper or plastic it can burst if safety valve not fitted.
  13. Heat

    Heat Screwfix Select

    Probably your soldered joint that blew off wasn’t soldered properly.
    Nearly impossible to have a properly soldered joint leak or break apart except if serious freezing.
    Lucky I guess you had a weak point in system though to release the pressure

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