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Pilot on but burners won't come on

mel rowe
mel rowe Member Posts: 324
in THE MAIN WALL
Honeywell T-87 stat. It is getting signal from stat. Combustion air unit comes on and everything looks normal, except no flame. Gas valve switch is set to on. Unit went off early this am. I removed thermocouple and inspected it. Changed out to a new one. Pilot is on. Main burners won't come on. Would low gas pressure do something like this? Or could the gas valve have failed?

Comments

  • mel rowe
    mel rowe Member Posts: 324
    Pilot on but burners won't light

    Appreciate any ideas as to what to check for. Noticed house getting cold. Checked boiler and found pilot okay, but no flame at burners.
  • ed wallace
    ed wallace Member Posts: 1,613
    no heat

    bad tstat is it a digital tstat? cange the batteries or bad thermostat wires is the gas valve switch set to on?
  • PLUMBARIS
    PLUMBARIS Member Posts: 22
    No Flame

    This unit has an inducer and a standing pilot?If so must be older unit. Things to check, connecting tube inducer to pres. switch Ihave hadline plug at exit to inducer, switch must prove before unit fires. Is there 24v at gas valve.if so and no fire bad gas valve.
  • Mark Eatherton
    Mark Eatherton Member Posts: 5,858
    Roll out switch at draft hood?

    Usually the LAST thing I check...

    ME

    There was an error rendering this rich post.

  • mel rowe
    mel rowe Member Posts: 324


    Thanks to all for helping me track it down. Found no current to gas valve. Traced back and found that the combustion air make-up unit had a problem with the fan switch. May be related to getting buried with snow off the roof last night. At any rate, jumpered it out and heating up again.
  • Jack Smith
    Jack Smith Member Posts: 53
    Did you dig it out!

    Not sure what you're describing, but if you jumped it out, I hoped it wasn't a safety.
  • mel rowe
    mel rowe Member Posts: 324


    No, just jumpered past the fan switch in the combustion air make-up unit, until I get a replacement part. Thanks.
  • Jim Franklin
    Jim Franklin Member Posts: 170


    Is it just a bad pressure switch or is the pipe still plugged with snow?

    If it's still plugged and doesn't clear your gonna die!!

    When jumping safeties you always flirt with danger.
  • mel rowe
    mel rowe Member Posts: 324


    Thanks for your concern. The intake line is clear of snow. The unit operates okay, except that it apears to have a blown relay and that is why it doesn't allow current flow to activate the gas valve. I also have a CO detector in the boiler room.
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