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90+ Gas Furnace Misfiring (flames sputtering)

csp02csp02 Member Posts: 3
What would cause a 90% gas furnace to misfire? As soon as the burners ignite the flame “sputters” (misfire), blower is not running.


  • JUGHNEJUGHNE Member Posts: 5,124
    A number of things;
    dirty burners
    gas pressure not right
    inducer fan
    cracked heat exchanger
    probably more

    What does the flame do when the blower comes on?
  • csp02csp02 Member Posts: 3
    The burners don’t stay on long enough, so the blower doesn’t have a chance to come on
  • JUGHNEJUGHNE Member Posts: 5,124
    Does this have a Honeywell Smart Valve on it?
    Picture of gas valve would
  • csp02csp02 Member Posts: 3
    I found the problem. Water in the pressure switch hose, which was caused by a clogged drain line. Thanks for the help
  • DZoroDZoro Member Posts: 565
    Glad you found it, just good ole annual maintenance. Grab the owners manual and you will find more to do. Or even better call a tech and have them go over it, they will check all of that and more, but mostly determine if it truly is operating safely. :)
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