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Steam Boiler short cycles...30 seconds or less

30 yr old residential one pipe steam boiler system.
Turning on and off constantly.
Some times the burners do not get fully lit before turning off.
A slight gas smell from the burners not fully lighting.



  • Jamie Hall
    Jamie Hall Member Posts: 18,958
    Almost certainly a controls problem, probably in the ignitor or flame detector or gas valve. But which one? Unless you are very comfortable troubleshooting, might be a good time to get a qualified gas burner tech. in to take a look? And maybe clean the boiler and adjust everything while he or she is at it?
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
    JUGHNE Member Posts: 9,765
    The first thing that comes to mind is the flame sensor.
    It is a metal rod that has to be in the pilot flame to keep the gas valve on. Often simple cleaning will fix your problem.

    Can you see the pilot/igniter assembly mounted on the burners?
    A picture of it and also the control module might help.
  • appletaxi
    appletaxi Member Posts: 2
    Technician found the the Low Water Sensor was gunked up. Drained system and cleaned. Running fine now.