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My hot water tank pilot light would go out. I could relight it and the burner would come on and heat up the water tank, but then later on, I would find there was no hot water again and find that the pilot light was off again. It was doing this for a week.

I replaced the thermocouple and all has been working fine for over a month now.

If I could light the pilot light and have it stay on and have the burner heat up the water tank. The thermocouple seems like it worked. I didn't think a thermocouple could be partially broken; I thought it either worked or didn't work.

So can a thermocouple be half broken?

Or is it more likely that replacing it fixed another problem, like a partial blockage in the gas line or something?

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up vote 2 down vote accepted

The solenoid will require a certain voltage range from the thermocouple in order to operate. If the thermocouple fails to produce that voltage range, then yes it could be considered partially "broken". You can probably find the expected output in the service manual and test it with a multi-meter in order to rule this in or out.

It could also be an issue with the position of the thermocouple, a problem with the valve, low pressure or some sort of safety mechanism. Does your water heater provide any indicator lights to help you diagnose what is going on?

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no lights to indicate anything – RyanWinchester Feb 14 '13 at 1:44
A cold water heater makes hot water. What does a hot water heater make? Steam? – Michael Karas Feb 14 '13 at 6:44

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