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The Case of the Unopening Gas Valve, this weeks case

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RayWohlfarth
RayWohlfarth Member Posts: 1,552
In this case, the customer had one boiler not working. My diagnosis was the one gas valve was defective. I had gas pressure before the valve and power on the valve and no gas after. After changing the gas valve with another, the problem persisted. What do you think caused the issue? I'll let you know what I found on friday morning at 6am EST

Ray Wohlfarth
Boiler Lessons

Comments

  • ratio
    ratio Member Posts: 3,696
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    Vent line was plugged. I did that once, too—now I have a spare valve.
    EBEBRATT-Edttekushan_3
  • retiredguy
    retiredguy Member Posts: 930
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    I agree with @ratio although he must have gotten out of bed before me. It could also be that the adjustable gas bleed orfice was closed. (same as the first answer)
  • JUGHNE
    JUGHNE Member Posts: 11,105
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    Surely someone reset the low gas pressure cutoff, if present.

    No voltage at valve would have shown that though.
  • HVACNUT
    HVACNUT Member Posts: 5,888
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    Where is pressure being tested after the valve? There's no manifold test port on the valve? Was it tested near the valve or at the end of the train?
  • EdTheHeaterMan
    EdTheHeaterMan Member Posts: 8,166
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    I think it's magic

    Edward Young Retired

    After you make that expensive repair and you still have the same problem, What will you check next?

    Solid_Fuel_Man
  • EBEBRATT-Ed
    EBEBRATT-Ed Member Posts: 15,835
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    Vent plugged agree wit @ratio
  • RayWohlfarth
    RayWohlfarth Member Posts: 1,552
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    Well @ratio was the first correct answer and the gas train vent was plugged. I too have a spare valve because I missed the diagnosis. I keep it on the shelf in my office to remind me. Im glad it wasn't a 3 or 4" gas valve. At the end of the video I share the formula I use when sizing the gas train vents.
    Here is the link to the video. https://youtube.com/watch?v=Eu6gj1gUQrQ
    Ray Wohlfarth
    Boiler Lessons
    ratio
  • ratio
    ratio Member Posts: 3,696
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    The end of the vent line was plugged so tight that I ended up making an adapter from ¼ compression to ¼ flare & blowing it out with N₂. I think I ended up at around 200 psig before the cork popped.
  • JUGHNE
    JUGHNE Member Posts: 11,105
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    I should have remembered the plugged vent scenario after an ice storm covered a NG regulator vent over solid with ice one miserable night.

    I did consider the USMC method of cooling the 30 caliber machine gun barrels to unthaw the ice. ;)
    PC7060Solid_Fuel_Man
  • RayWohlfarth
    RayWohlfarth Member Posts: 1,552
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    @ratio Thats incredible how they plug like that in a relatively short time. Never had to use that much pressure LOL
    @JUGHNE Sounds like a terrible service call. I like your idea of using the USMC method LOL
    Ray Wohlfarth
    Boiler Lessons
  • EBEBRATT-Ed
    EBEBRATT-Ed Member Posts: 15,835
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    Bees, wasps and ants love small vents.

    One reason MA specs vents mut be 3/4" IPS or larger if they exceed 40'
  • RayWohlfarth
    RayWohlfarth Member Posts: 1,552
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    @EBEBRATT-Ed Yep discovered that on this job. Thanks
    Ray Wohlfarth
    Boiler Lessons