termocoupler keeps goin bad

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termocoupler keeps goin bad

Postby tomsteve » Fri Feb 11, 2011 8:52 am

i have a goodman furnace with a standing pilot. i have had to replace the thermocoupler 3 times in the last 4 weeks, and the pilot went out and wont relight. i know if i replace the thermocoupler again, it will relight. it's pretty friggin cold here in northern michigan and i think theres a deeper problem. i'm pretty mechanically inclined, but sure could use some direction here. any and all advise will be greatly appreciated.
the pilot flame is big and blue. now, i have heard 2 different ways the thermocoupler chould be installed. either with the tip just brushing the flame or with the the t.c. completely in the flame. which is the right way?
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- termocoupler keeps goin bad

Postby 4ftBanger » Fri Feb 11, 2011 10:43 am

A thermocouple works by generating a small electric current when the two metals it is made of are heated, so the more contact it has with the pilot flame, the more efficiently it will be able to generate the current. There are thermocouples, typically in gas logs, that are referred to as Oxygen Depletion Sensors (ODS) that should only contact the pilot flame with the tip of the thermocouple, but in standard vented appliances the thermocouple should be pretty much bathed in flame.

Based on what you describe, I'd say you more likely have a problem with the gas valve itself. The gas valve holding coil may be weak and closing the pilot valve.
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- termocoupler keeps goin bad

Postby tomsteve » Fri Feb 11, 2011 11:15 am

thanks, matt. i had to get the thermocoupler in and get the heat on. gettin a little chilly in here and i was harin it fromt he family. it's supposed to warm up next week and think i'll go ahead and repace the valve. i also heard i could go to a pilotless valve. is that possible?
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- termocoupler keeps goin bad

Postby nomadpeo » Sun Feb 13, 2011 10:07 am

observe the pilot/burners durning the course of the cycle. is thee a significant movement of flame when the fan comes on ? when is the pilot shutting down, during the off cycle or when the burner cycles off ? is the thermocouple fully enveloped in the pilot flame and does it stay enveloped during the heating cycle ? is anyone getting headaches or feeling confused ? if the heat exchanger has a crack, it could affect the pilot flame stability as well as introduce carbon monoxide into your air stream. we want to help and we want you to be safe. observe the cycle from start to finish and let us know what you see happening. to be safe, you should have a professional test your system. by the way, what is the age of your furnace ? it should be encoded in the serial number.
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- termocoupler keeps goin bad

Postby tomsteve » Tue Feb 15, 2011 10:51 am

it went out again and wont relight. the thermocouple is fully enveloped in the pilot flame, but i havent looked at how the flame is acting through the cycles. i have a carbon monoxide detector right in the utility room and it hasnt gone off or shown any high readings on it. as for headaches, no. confusion? well, my mom lives with me and has dimentia, so she's always confused, and i have only been normally confused. not sure of the age of the furnace yet. the serial # is 91083246B. i'm not able to purchase a new furnace at this time.
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- termocoupler keeps goin bad

Postby nomadpeo » Tue Feb 15, 2011 11:35 pm

sounds like you probably need a gas valve.
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- termocoupler keeps goin bad

Postby tomsteve » Fri Feb 18, 2011 1:12 pm

of all things, i had to order a gas valve! not one in a 45 mile radius of here. and it's taken 4 days to get here. good thing we've had a warm spell lately.
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