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Gas furnace take multiple times to light

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  • Gas furnace take multiple times to light

    I have a York M3CF032AA gas furnace that sometimes I have to turn the thermostat on and off 3,4,5,6 times until I get a flame. Other times, it will work a week without issue.

    I fix CNC machines and I know those, but when it comes to furnaces and such, I am pretty new. I have been watching the cycle and it appears to me the following takes:

    1)Turn on thermostat
    2)Furnace comes alive
    3)After about 40 seconds, I see the igniter glow bright red
    4)I then hear a click which I am assuming is the gas being allowed to flow
    5) As soon as I hear that click and the gas flow, the igniter pretty quickly dims down

    Then either....

    6a) Within 3 seconds of click, flames ignite, blower comes on, AHHH the joys of heat

    6b) Within 3 seconds of click, no flames, furnace stays on, "time to double up on the layers honey"


    As I said, its really a toss up as to whether 6a or 6b happens. The igniter consistently glows and I am assuming if it wasnt reaching proper temps, the gas would not even be allowed to flow.

    So my question is, I have been reading something about the gas valve possibly not opening up enough to let enough gas through in time and that you can check that with a meter. Can someone enlighten me on that.

    Or do you guys think I need to clean out the burners? Whats more likely? And if it is cleaning the burners, is that something I can do safely? Thanks!

  • #2
    Re: Gas furnace take multiple times to light

    If not igniting, could be:

    - improper voltage (ignitor should be white hot, not red)
    - low gas pressure
    - dirty burners, cross lighters or orifices
    - bad pressure switch
    - partially plugged venting
    - bad gas circuit on board
    - bad gas valve
    - weak ignitor (glowing doesnt mean enough heat)

    if igniting, could be:

    - bad flame sense (ignitor or dirty flame sensor)
    - bad circuit board

    To test gas pressure you need a water column gauge and a working knowledge of Heating 101. It's not something I will teach to a novice. Turning the thermostat to off, then back to on, will reset most circuit boards. The unit then retries for heat.

    Once a furnace experiences an ignition failure you really need a professional clean and check. The pro will also catch things you do not know about or recognize and will save you money and trouble in the future.
    ~~

    ... it was plumbed by Ray Charles and his helper Stevie Wonder

    Comment


    • #3
      Re: Gas furnace take multiple times to light

      If your pilot light is on that means your igniter is igniting the gas.
      And that the gas is somewhat flowing to your burner.
      But if your pilot light is on and the burner is going off the problem is with the gas flow to the burner.
      Specifically with your gas valve to the burner.
      The vents blowing cold air means your fan is working but not your burner.
      Knowledge speaks, but wisdom listens.

      Comment


      • #4
        Re: Gas furnace take multiple times to light

        Originally posted by rickymartin85 View Post
        If your pilot light is on that means your igniter is igniting the gas.
        wrong. it means the pilot is burning gas. prelit by the tech or other means. his furnace is direct ignition and has no pilot.


        And that the gas is somewhat flowing to your burner.
        wrong. the main burners do not always light. the pilot is only a fail-safe to tell a non-direct ignition furnace that an ignition source is present. gas does not 'somewhat flow' to a burner only because the pilot is lit. again, there is no pilot in this situation.


        But if your pilot light is on and the burner is going off the problem is with the gas flow to the burner.
        wrong. there are other reasons, such as bad flame proving or low voltage


        Specifically with your gas valve to the burner.
        wrong. see above.


        The vents blowing cold air means your fan is working but not your burner.
        no kidding!

        Knowledge speaks, but wisdom listens.
        you need more wisdom.
        Last edited by Plumber Punky; 05-17-2013, 09:42 AM.
        ~~

        ... it was plumbed by Ray Charles and his helper Stevie Wonder

        Comment


        • #5
          Re: Gas furnace take multiple times to light

          Originally posted by Plumber Punky View Post
          wrong. it means the pilot is burning gas. prelit by the tech or other means. his furnace is direct ignition and has no pilot.


          wrong. the main burners do not always light. the pilot is only a fail-safe to tell a non-direct ignition furnace that an ignition source is present. gas does not 'somewhat flow' to a burner only because the pilot is lit. again, there is no pilot in this situation.


          wrong. there are other reasons, such as bad flame proving or low voltage


          wrong. see above.


          no kidding!

          you need more wisdom.
          One of the risks of info on the net as that it is also full of incorrect advice. There is another forum around that I stopped visiting as I found the advice given questionable and in many cases unhelpful. Part of the challenge in participating in forums is to find good forums with good and solid discussions. Before I join a forum I usually read through the threads as you can get a feel for the forum participation and if it is forum worth joining. This is a good forum but from time to time I do see people posting advice on topics they do not know much about. I know the purpose of some is to find an excuse to drop links by posting some sort of advice - very inconsiderate to the person asking for advice.

          Comment

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