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Discuss OSO unvented cylinder in the Plumbing Forum area at

  1. pmplum

    pmplum New Member

    I have customer with a 330 litre OSO Invented cylinder with water coming from the cold water expansion valve.
    My question is these cylinders have an internal expansion “bubble” , can they fail ?
    Tried draining it and refilling to recharge the bubble
    Checked hot ware temp and it’s at 60 so not over heating
    Question is about the internal expansion bubble
  2. Gasmk1

    Gasmk1 GSR

    i thought oso vessels were external ?
    • Agree Agree x 1
  3. pmplum

    pmplum New Member

    This one on the 330 litre is internal
    It’s about 8 years old
  4. SavageW

    SavageW Plumber GSR

    The relief valves are notorious for passing once they have discharged,you could have recharged the bubble correctly just the valve has not reseated
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