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Why does your gas hot water heater pilot keep going out?

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Wiki User
2012-08-14 03:17:58

  • This is usually caused by a bad thermocouple. The thermocouple

    looks like a thick, solid copper wire screwed into the gas valve on

    the water heater. The pilot flame heats the tip of the

    thermocouple, causing it to generate a minute electrical current at

    low voltage, which provides power to an electric valve that

    controls the flow of gas to the main burner. If you attempt to

    relight the pilot burner and it refuses to stay lit when you

    release the button on the gas valve a minute, or so, after the

    flame has been lit, the thermocouple is the most likely cause.

    Replacement thermocouples are readily available from most hardware

    stores and can be replaced by the homeowner, using simple tools, by

    following the instructions on the package.

  • Another cause of the problem could be a lack of air to the

    combustion chamber. Newer water heaters require more volume of air

    due to the addition of a heat sensitive diode to the thermocouple.

    Not enough air flowing through the combustion chamber to carry the

    heat up through the flue causes heat build up, which kills the

    thermocouple. On my water heater, I could light the pilot and the

    water heater would burn for 20 minutes or so and shut off. The fix

    included routing the flue straight through the roof and opening

    floor to allow more air into the water heater compartment.

  • Another possible culprit may be water-heater vent height above

    the roof. In some situations this may periodically result in a

    downdraft that could cause the pilot light to go out. If this is

    the case adding to the vent height may help. Note: building code

    states that the B vent required height is based on the roof pitch

    but it must be 2 feet higher than any portion of the building

    within 8 feet of the vent.

  • Make sure the vent cap isn't missing or rusted through on the

    roof, it will cause drafts and wind to blow out the pilot.


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