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Water Heater Thermal Coupler Keeps Going Out?

Anyone have any ideas why I keep needing to replace the thermal coupler on my hot water heater? The water heater is six years old and I’ve replaced the thermal coupler 3 times in the past year. Is there another problem I should be looking in to? Or is this somewhat common?

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  1. Comment by KTB
    January 27, 2010 @ 3:05 pm

    Chances are VERY good it is one of the following. Here’s what you do,
    Always turn off the gas supply, before beginning, when necessary…..
    1. Check the pilot light. If the flame is too weak, it will be blue, but barely touch the thermocouple. If it is too strong, it will still be blue, but it will lift off the pilot and will likely be a little noisy.
    A well adjusted flame, will be blue, but with a yellow at the tip. It will also cover approximately 1/2″ at the end of the thermocouple. Adjust the flame (pressure) until you see this at the control housing (gas valve) until you see this. If it doesn’t work, remove the pilot jet and clean.
    2. If you have done the above, and it still isn’t right, adjust the air shutter at the end of the burner tube.
    Start by setting your thermostat on high. Carefully unscrew the locking screw, open the shutter WIDE, and close slowly until you see the proper flame as described above. Repeat the procedure for any remaining burner you may have.
    3. If you still have issues, remove the burners all together. Put them is a tub with warm water and soak for a while. Clean with a soft-medium bristle brush (including each spud) let dry and replace. Remember, do not over-tighten. Just replace until very snug.
    4. An over active igniter can be the last problem. If all else fails, replace this part. This is the least likely problem.
    The first two issues are the likeliest causes as they will result in a thermocoupler going bad. The third can cause back pressure, resulting in an overheating at the feed (pilot) as well, but it is a less likely cause than the first two. The fourth, other than calling in a serviceman, is the only other cause I can think of.
    Feel free to write me, should you have any further question(s). I’ll be glad to help.

  2. Comment by Mr Unlizzard
    January 27, 2010 @ 4:47 pm

    your pilot flame is to large? is it melting? or your just mot generating milivolts with it? over tightening the connection?could be a weak safety valve as well. as thermal couples get older, they loose some ability to generate enough . and if the safety valve is also weak this could make it seem like a bad thermal couple

  3. Comment by nosdda
    January 27, 2010 @ 4:53 pm

    Make sure that the pilot light is directed right onto the Thermocouple, and it is a nice blue flame. A yellow flame will cause sooting on the thermocouple and it cannot transfer the heat to the gas valve.

  4. Comment by cclltt
    February 17, 2010 @ 9:53 am

    i had a simular problem with mine replaced the thermocuplin worked for a while but went back out. i happened to look at the door on the water heater closet and seen the vent stopped up with dust from sweepin the floor. i cleaned it off didnt replace the thermocuplin lit it andit is still burnin today. my wife keeps the vent clean when she sweeps now. heater is 10 years older now and still workin.

  5. Comment by michael
    February 4, 2011 @ 4:28 pm

    our water hearet went out when austin tres to conserve energy it doest let us keep the boileer light up

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