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Tanklets > Pilot Light Issues

Q: I have a State Select GS640YBRT. I have just replaced the gas control valve and the thermocouple kit they sell for it (the universals don't work or something in these, so I had to buy the $60 kit).

Everything is hooked up correctly. used the leak check liquid to make sure no leaks. Of course I refilled the water heater as well. I see the spark. I see the gas pilot light light. It will stay light without flickering as long as I hold the pilot light button down, but as soon as I let the button up, the pilot light goes out.

I have held it down for up to 2 minutes and it still goes out the second I let off the button.
What am I doing wrong here?

Q1: UPDATE: Took the burner unit out, and bent the little arm that holds the thermocouple to make sure that it was sufficiently in the heat.

Same thing continues to happen. Pilot light will light, but only as long as we depress the pilot button.

A: I'd make sure the thermocouple is being nicely heated. It actually should glow a very dull red. It's best if the pilot flame wraps most of the way around the tip of the thermocouple. Attached is a photo (at right). Is yours anything like that? (Larry Weingarten)

Thermocouple in pilot light flame

Q2: OK, so the thermo has NOT glowed red like that, but it is definitely fully in the flame. The flame looks more like a teardrop. Tomorrow I am going to try and see if I can get a good pic of it (I had the "door" not screwed in so I could see the pilot light lit and know the exact location of the thermo in it).

I may have the light hitting too far down the therm and not on the tip. I will check that as well. Thanks for the response. My friend and I consider ourselves pretty handy, and this is driving us nuts.
I will include pictures of everything tomorrow, since I will be taking the burner assembly out again.

A1: Hi, You might also want to be sure the thermocouple, where it screws into the control is clean and snug. I usually just wipe the end of the thermocouple with a knife so it shines and screw it in snugly, so it makes good contact. Also, you could heat the tip of the thermocouple and use a meter to measure millivolts or milliamps to see if it really is generating some electricity. :cool:  Here's a link that might help: https://www.hunker.com/13414881/how-to-test-a-thermocouple-with-a-multimeter . (Larry Weingarten 6/18/20)