Furnace will not stay lit

Discussion in 'Heating / Cooling Systems' started by khawk, Mar 2, 2008.

  1. khawk

    khawk New Member

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    Need help. The furnace in our '05 Flagstaff HW will not stay lit.
    I turn on the thermastat, the fan comes on for a minute, then the
    igniter starts and the furnace ignites. It works for about 30 seconds and then goes out. Then in a couple minutes the igniter will
    light it again and the process repeats. Has anyone had this problem or are there any suggestions that I can tackle without a trip to the shop?
    I did take off the little door with the glass window to the burner and blow out with a air hose, but it did not help.

    I would appreciate any help.
    Thanks

    Keith '48
    Sherry '49
    '05 Flagstaff HW 625D
    '07 4Runner SR5 V6
     
  2. John L

    John L New Member

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    If it lights for a few minutes and then goes out you may have air getting into the gas line or it could be a bad sensor. Does you gas stove in the camper work alright? Try lighting a stove burner and let it run for a few minutes to see if it stays lit. Don't light anything if you smell gas.

    I'm sure others will have some ideas as well.

    John & Kitty (Empty Nesters)<img src=../Images/icons/icon_smile_camping.gif border=0 align=middle alt="Camping">
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    Edited by - John L on March 02 2008 17:45:41
     
  3. khawk

    khawk New Member

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    I did try the stove burners and all worked perfect. Also tested the
    fridge in the gas mode and it seem to be working fine.
    Where is the furnace sensor and is there a "do it yourself" test for it?

    Thanks for the suggestions.

    Keith

    Keith '48
    Sherry '49
    '05 Flagstaff HW 625D
    '07 4Runner SR5 V6
     
  4. ogeer3

    ogeer3 New Member

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    Make sure the thermocouple is good that checks to make sure the pilot has not gone out. Also most furnaces have an air flow sensor to make sure the fan is blowing enough air through the furnace. If this is not being deflected enough by the fan it will shut off the gas for safety reasons.

    Happy Camping!

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  5. Micksc

    Micksc New Member

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    From the way you have described your symptoms your furnace is DSI or "direct spark ignition". This being the case you wouldn't have a thermocouple but a "flamerod" or flame sensor that tells the controller that a flame is present. The short burn interval is called "trial for ignition" which is a preset time until the unit goes into safety shutdown. Look for a "normal" looking wire, as opposed to one that looks like a sparkplug wire going from the combustion area back to the controller. If it isn't firmly connected at both terminals that could be the Prob. If all connections are tight then try replacing the sensor.

    Me'42
    DW'42
    00 Coleman Cheyenne
    04 Iszusu Ascender
     
  6. khawk

    khawk New Member

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    Mick,
    Thanks for the info, you're correct I do have DSI, I'll check tonight
    when I get home for the wire going to the controller.

    One question, The space is tight for a visual check, Can the furnace
    be slid out? It is to the left of the fridge & close to HW heater, I don't won't to pull any propane connections loose.
    I do see a couple of screws in the front just behind the cover that look like they sucure the furnace housing to the floor. I am assuming if the screws are removed it should slide
    out. Correct?

    Thanks to all who have replied,
    Keith

    Keith '48
    Sherry '49
    '05 Flagstaff HW 625D
    '07 4Runner SR5 V6
     
  7. Micksc

    Micksc New Member

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    Keith, I've never pulled one of these camper furnaces out so can't help you with that. The gas connection SHOULD have some sort of quick disconnect, but then you're gonna need to hook it back up to bench test it. I do HVAC/Elec. for a living and most DSI furnaces operate alike.
    Mick

    Me'42
    DW'42
    00 Coleman Cheyenne
    04 Iszusu Ascender
     

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