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    Oil Boiler Leaking Water (5 Posts)

  • DB77 DB77 @ 8:49 PM
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    Oil Boiler Leaking Water

    My oil boiler is leaking water.

    I have water leaking from the pressure relief valve at a pretty steady
    pace. It fills up a large mop bucket in about 2-3 days time.

    The expansion tank on the oil boiler was mounted sideways rather than
    vertically. It is unsupported and is sagging. However when the near side
    of the tank (what would be top if mounted vertically) is hot while the
    far side (what would be bottom if mounted vertically) is cool and it
    does sound like there is air in the tank when performing the knock test.
    This seems to indicate a working expansion tank. Does this mean that
    the expansion tank is not likely the cause of the PRV leaking?

    Another symptom is that the system always seems to have zero pressure
    according to the boiler pressure guage. I believe the pressure guage is
    working because if I hold the pressure valve open I can see the pressure
    increasing on the guage.

    Any ideas on what might be causing the leaking and zero pressure?

    Thanks guys
  • Paul48 Paul48 @ 8:57 PM
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    Replace the PRV.Sometimes when they discharge, they will not seal afterwards. Replace and properly mount the expansion tank. Is there a coil for domestic hot water in the boiler?
  • billtwocase billtwocase @ 9:29 PM
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    agree with Paul

    sounds like a water logged extrol, lazy feed valve
  • northernboiler northernboiler @ 12:40 AM
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    I agree but would go one further..

    I would replace what I like to call the "holy trinity"
    Replace the water feeder, expansion tank & PRV.
    The water feeder is not operating properly anymore if you have to manually open it to add water. The diaphragm in the expansion tank is most likely blown due to over pressurization The relief valve is probably not seating correctly anymore from it weeping so long or too many times.
    In my experience, a situation like this is like a chain reaction, the water feeder goes bad, it ends up blowing the expansion tank, and then to relieve the built of pressure in the system, the PRV "weeps". And with correct pressure or not in the boiler, doesn't stop leaking.
  • Jean-David Beyer Jean-David Beyer @ 9:09 AM
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    And with correct pressure or not in the boiler, doesn't stop leaking.

    I bet it will stop leaking after a while, when the calcium deposits build up and seal it off.

    Then, when the aquastat sitcks on, the excitement will start. Call in the mythbusters.
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