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I have a Condensing gas fired wall mounted boiler does DHW, radiant floors as well as central heat

The brand is Baxi Luna 1.330 Recently I have noticed the gauge on the front of the unit has been indicating higher pressures. (I not even sure what it measures)
range of the gauge is 0 - 4 bars with the operating range (green area) 1 - 1.5 ish.
Although everything seems to be operating fine the gauge is showing well into the red at 4 +
I am hoping to find the cause of the high reading. Possibly a failed gauge ?
Any advice I can get before calling some on in would be appreciated. I don't want to find the basement full of water :(

Comments

  • hot_rodhot_rod Member Posts: 12,897
    I think that unit has a small expansion tank inside, check to see if has failed
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    The magic is in hydronics, and hydronics is in me
    SuperTechkcopp
  • ggpartsggparts Member Posts: 3
    To find the small expansion tank what would I look for?
  • Jamie HallJamie Hall Member Posts: 12,345
    ggparts said:

    To find the small expansion tank what would I look for?

    Take a look and see how the pressure changes from when the unit is cold -- let it sit off for a couple of hours -- and then as it warms up. Shouldn't change that much -- half a bar, perhaps.

    Also... how is water added to the system? If it's through a pressure reducing valve, that valve may be leaking past.
    Br. Jamie, osb

    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England.

    Hoffman Equipped System (all original except boiler), Weil-Mclain 580, 2.75 gph Carlin, Vapourstat 0.5 -- 6.0 ounces per square inch
  • ggpartsggparts Member Posts: 3

    ggparts said:

    To find the small expansion tank what would I look for?

    Take a look and see how the pressure changes from when the unit is cold -- let it sit off for a couple of hours -- and then as it warms up. Shouldn't change that much -- half a bar, perhaps.

    Also... how is water added to the system? If it's through a pressure reducing valve, that valve may be leaking past.
    This is the only source of heat for my home, I hesitate to turn it off. Not sure if there is a PRV or not.
  • bennyboybennyboy Member Posts: 7
    I agree... you heat water and it expands thus pressure goes up. Something is preventing the expansion tank from working or the expansion tank isn't working.
  • SuperTechSuperTech Member Posts: 1,209
    Sounds like your expansion tank has failed. Baxi usually has a expansion tank built in to the boiler they can be a pain to service. I would just install one on the boiler supply piping.

    Your boiler better have a pressure relief valve that should open up after the boiler pressure exceeds 3 bar. If it doesn't shut it down immediately and call for service because it's extremely unsafe to operate.
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