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90+ Gas Furnace Misfiring (flames sputtering)

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csp02
csp02 Member Posts: 3
in Gas Heating
What would cause a 90% gas furnace to misfire? As soon as the burners ignite the flame “sputters” (misfire), blower is not running.

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  • JUGHNE
    JUGHNE Member Posts: 11,061
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    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?
  • csp02
    csp02 Member Posts: 3
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    The burners don’t stay on long enough, so the blower doesn’t have a chance to come on
  • JUGHNE
    JUGHNE Member Posts: 11,061
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    Does this have a Honeywell Smart Valve on it?
    Picture of gas valve would
  • csp02
    csp02 Member Posts: 3
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    I found the problem. Water in the pressure switch hose, which was caused by a clogged drain line. Thanks for the help
  • DZoro
    DZoro Member Posts: 1,048
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    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. :)
  • jgodina
    jgodina Member Posts: 7
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    My self ingniting gas furnace flames stays burning when the flame inspection cover is off.but when you put the cover back on,the flames go out.could it be the ingniting rod?it seems it's starving for air when the cover is on,but thrives without it.it ran good for a month.and then this happens.thanks
  • Zman
    Zman Member Posts: 7,569
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    @jgodina
    You will get better results if you start a new post rather than piggybacking off an unrelated one.
    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
    jgodina
  • jgodina
    jgodina Member Posts: 7
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    Thanks.i haven't figured out how to start my own post.
  • Zman
    Zman Member Posts: 7,569
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    You use the orange "New Discussion" tab on the upper right.
    With your new post, pictures would be helpful. It sounds like you have a sealed combustion unit? I would first check for blockage in the combustion air piping.
    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
  • JUGHNE
    JUGHNE Member Posts: 11,061
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    Z-man, he did re-post his own.
    Cleaned air/vent hoses to pressure switch.
    Zman

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