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Weil mclain ultra 155

I've been working on this boiler for almost 2 weeks. I've replaced all the gaskets cleaned the heat exchanger replaced the ignition cord and the ignition itself. I get it to fire sometimes but will only last about a day then goes back into ignition fault. Any ideas? 


  • Ironman
    Ironman Member Posts: 7,350
    Was a combustion analysis done?
    Bob Boan
    You can choose to do what you want, but you cannot choose the consequences.
  • EdTheHeaterMan
    EdTheHeaterMan Member Posts: 7,565
    What does "replaced the ignition itself" mean? Are you speaking of the Ignitor/flame sensor and gasket the goes thru the door near the flame view port? ...or the electronic control board the creates the spark?

    Part of the flame sensing circuit is the Chassis Ground. Is there any corrosion on any of the screws that hold the flame sensor on the heat exchanger? is there a good ground connection to the control board? sometimes I have corrected the Flame Rectification Circuit on old equipment by installing a dedicated ground wire from the flame sensor to the control board ground connection.
    Edward F Young. Retired HVAC ContractorSpecialized in Residential Oil Burner and Hydronics