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Pressure Guage Bouncing

Al K._2
Al K._2 Member Posts: 27
in THE MAIN WALL
While on an annual service call, while checking the operation of the system, I noticed the pressure gauge (water boiler)bouncing two or three pounds up and down near the end of the run cycle. As the burner shut down, I could hear a slight boiling sound. Turned down the aquastat (WAY down), problem is still there. thermometer only reads 190-200, pressure aprox 12#.
Customer says, oh yeah, the pipes in this room only make funny gurgling sounds.
Scaled boiler or tankless coil?
Defective gauge?
Defective aquastat?
All the above, or something else?
I'm leaning to the scaled or dirty boiler, but what do you guys/gals think?
Thanks,
Al K.

Comments

  • DanHolohan
    DanHolohan Member, Moderator, Administrator Posts: 16,610
    Sounds like

    the water is flashing to steam, which would indicate poor circulation through the boiler.
    Retired and loving it.
  • Al K._2
    Al K._2 Member Posts: 27


    Thanks Dan, I'll look into the circulation issue.
    Al K.
  • sootmonkey
    sootmonkey Member Posts: 158
    psi bounce

    my first bet would be that the extrol tank is bad. drain the presure off of the system and put a pressure guage on the extrol tank. i would also take a close look at the air vents. dont ask me why, but i have seen many boilers that over ride their aquastat settings, and it is because the extrol tank has only a pound or two of psi in it. i know it doesn't make sence to me either. just what ive seen. keith
  • J.C.A._3
    J.C.A._3 Member Posts: 2,980
    Hey Al, can I take a guess?

    Is this a Teledyne/Laars JVC or the newer grey colored one model? Chris
  • Al K._2
    Al K._2 Member Posts: 27
    Chris...

    The boiler's a S/F Liberty L30.
    And, I'll check the pressures of boyh the water side and the expansion tank air-side. Thanks for the suggestion.
  • sootmonkey
    sootmonkey Member Posts: 158
    Al K

    Dude, here is the story of my Slant Fin Liberty 30. The unit has always "steamed". This is a hot water boiler. Things I have done to it...#1 repipe to pump away. #2 air vents to book. #3 New aquastat. #3A Replace # 30 extrol tank. #4 turned aquastat down till everyone gripped about no hot water. #5 washed water side with tsp. #6 increased water psi to 25. (lost psi due to steaminng out air vents) #7 increased psi on bladder tank to 20 psi. #7 seemed to do it, but now I think it has lost its air charge. Every Liberty 30 that I do a tune up on or have serviced "steams". By "steams" I mean makes percolating noises after burner shut down, lasting 30 secs or so. Just enough to distroy a air vent a year. Good luck, let me know what happens. Keith
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