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Steam Boiler short cycling for approx. 10 minutes then running normally

gprett Member Posts: 1
Hello, I am pretty handy but definitely not an expert in this! So hoping I can get some guidance. My steam (gas) boiler started short cycling on startup. It will kick on, run for about 30 seconds, then shut off, then repeat. This goes on for about 10 minutes, then the boiler runs as normal until the desired heat is reached.
I discovered a totally clogged pigtail, cleared it completely and reinstalled. I also drained the boiler and return lines to start fresh. I thought this would've solved the problem, but the boiler is doing the exact same thing (short cycling for 10 minutes then running normally). When running, the 30psi max gauge doesn't show any pressure, and the pressure troll appears to be in good working order (switch mechanism moves and there isn't any noticeable clog). Wondering what may be going on as I thought unclogging the pigtail would do the trick!


  • SteamingatMohawk
    SteamingatMohawk Member Posts: 1,006
    Loose wire somewhere that makes contact after the 10 minutes of the boiler and controls heating? Wild guess, but stranger things have occurred.

    Have you touched anything recently?
  • ChrisJ
    ChrisJ Member Posts: 15,677
    Is this a single pipe system?
    How are the main vents?

    Does it cycle like this before it starts producing steam?
    Single pipe quasi-vapor system. Typical operating pressure 0.14 - 0.43 oz. EcoSteam ES-20 Advanced Control for Residential Steam boilers. Rectorseal Steamaster water treatment
  • Jamie Hall
    Jamie Hall Member Posts: 23,289
    Back to square one. First thing to do is to find out which control or controls is shutting it off -- or if it is simply losing power.

    Then attack whatever is tripping the control...

    If it does this right away, I'd check the entire gas train and ignition system and burner controls, as well as the steam controls.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
    JUGHNE Member Posts: 11,061
    Was the pigtail piping clear all the way back into the boiler, that port is often overlooked.
    If you add a 0-5 PSI gauge you could see if it is a pressure short cycling issue or otherwise.
    EBEBRATT-Ed Member Posts: 15,525
    How is the boiler water level while this is going on?
  • neilc
    neilc Member Posts: 2,703
    flame rod needs cleaning,

    # new horses
    known to beat dead horses
  • neilc
    neilc Member Posts: 2,703
    post a picture of the burners / burner tray
    known to beat dead horses
  • pedmec
    pedmec Member Posts: 973
    pigtail. not completely plugged but moving ever so slowly back and forth. clean it or replace it depending if it comes clean