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Pilot light goes out

Please help! I have a gas warm air furnace with AC; every fall, after cooling season, in order to switch to heat, my pilot has to be relit, as it goes out on its own sometime during AC season. (this has been a recurrent pattern from initial installation) Once relit, there's no problem, as the pilot stays lit until the next AC season when it dissipates again. Any advice on why this is happening? It's easy enough to re-light each fall, but in selling my home, I want to correct the problem for the new owner, rather than have him continue to do as I've had to do. Please can anyone suggest what actions to take? I am most appreciative.


  • Don_4
    Don_4 Member Posts: 36

    Most commonly the pilot goes out due to an improper flame(dirty) or a poor thermocouple. It is easy to spot a dirty pilot, the flame has yellow in it (some orange is normal). This is assuming you do not have an issue with your heat exchanger (cracked, corroded). Regardless, you should have it checked by a Pro.
  • Cindy Gale
    Cindy Gale Member Posts: 2

    Don, you suggested replacing the thermo-couple, which will be the first plan of attack. Could you tell me what other symptoms I would be noticing if I had a cracked or corroded heat exchanger? And if that is what's causing the pilot light to go out between AC season and heating season, how is a damaged heat exchanger fixed? I'm sorry with all these questions.
  • Dave Flood_3
    Dave Flood_3 Member Posts: 7
    pilot light

    Hello Cindy,
    If you have a cracked heat exchanger, air will blow into the combustion chamber and blow out the pilot light. If the exchanger is cracked, I would recommend you replace the furnace.
    There are a few things that can blow out the pilot light. Chimney down draft. Wind blowing into the furnace room when the door is open. Do you have a whole house fan turned on in the summer creating a negative pressure in the furnace room. This can cause air to come down the chimney and blow out the pilot.
    I'd recomend you have a service tech come in and check.

    Good Luck
  • Brian_24
    Brian_24 Member Posts: 76

    If your return air duct is undersized and leaking you may be back-drafting your chimney. Not a good thing. You need to have the static pressure checked on your furnace and a draft test done on your chimney. Ifd it is back-drafting count your blessings tyhat the pilot light goes out. Good luck.
  • Cindy, is the AC coil

    installed just above the furnace in the duct work (called a plenum)? If it is then it is not unusual for it to have heavy condensate dripping down onto the heat exchanger. That alone if it is in a damp basement or crawl space area can cause the heat exchanger itself to sweat inside and drip down on the pilot and put it out. Others have advised concerning the integrity of the heat exchanger itself and that should be checked by a professional contractor proficient in the ability to recognize a damaged (cracked heat exchanger).

    The fact that the pilot stays on after it is relit for the heating season tells me that mechanically it is fine, if it was not it would keep going out. If you plan to sell the house a home inspector would probably recommend someone to test the heat exchanger for you.
This discussion has been closed.