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exploding pex

joel_19 Member Posts: 931
It was a 30lb relief


  • joel_19
    joel_19 Member Posts: 931
    exploding pex

    Ok i don't have the pictures here but I can tell you what happened . First it wasn't installed by us . Second i do not like this type of installation to begin with . It is a Utica oil , direct vent with tankless coil and has pex run to fin tube . I don't think this is a very good idea at all because the pex is rated at 180f MAX . The oil companies set the low limit on these at around 180 and high at 210+ to get enough water out of the tankless coil. To me that's just a bad idea . Feel free to kick in your two cents on that one .

    The aquastat failed and the relief valve did not do it's thing . our tech tested it and shut it down at 245f water and 45psi who knows how hot it got . But it scared the Beejesus out of the homeowner when the pex went kaboom (nice kaboom Wiley )and the basement filled with steam . The Pex melted or otherwise blew apart in essence becoming the relief valve. Question is did this terminally dammage the rest of the PEX ? Destroy the oxygen barrier ? What do you think? I can say it is way stiff now .
  • ed wallace
    ed wallace Member Posts: 1,613
    exploding pex

    I would say the pex is trashed the heat has affected all of it what was the relief vavle rating was it a 30 lb or was it the wrong one?

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  • Constantin
    Constantin Member Posts: 3,796
    I'd replace it...

    ... unless the manufacturer sends you a signed affadavit that the stuff will be fine despite the thermal event. After all, you own the installation once you touch it.

    In the absence of said affadavit, I would only work on this project if the PEX is replaced. Furthermore, if PEX is replaced for PEX, I would require a indirect water heater and an outdoor reset control, along with the proper near-boiler piping. At least that way you minimize the stress on the PEX to a few days a year, if that.

    This might head for law-suit-land, so take plenty of pictures of the before and after, document the issues, etc. to CYA in case the oil company gets sued by the homeowner.
  • Tim Doran
    Tim Doran Member Posts: 208

    If it is PEX-A there should be no loss of performance due to this overheat and the barrier is most likely uneffected. Thats the benefit of thermo-elastic memory achieved in the hot cross linking process.. Check with the manufacturer of the PEX as I can not speak to the effects of overheat on other types of PEX, however I would suspect that the effects are minimal.

    Tim D.
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