30b. flame ignites but goes out immediately when i realease the green button after 20 seconds. have replaced thermocouple but still no joy - any ideas ?
First, I'm assuming you have a residential Gas-Fired Heater or Water Heater that you are having problems with. My answer is based on this assumption.
Most thermocouples require that you hold the button for at least 45 seconds. Try holding the button for 60 seconds prior to releasing it. If this does not work, you can test your new thermocouple if you have a multimeter...preferably one with an alligator clip for your leads. To test your thermocouple, disconnect the end that screws into your gas valve. Set your multimeter to read Milivolts. Put your red lead on the copper line of the thermocouple.....it's easier if you have an alligator clip. With your pilot lit, hold down the button for 45 seconds and continue to hold while you put the black lead of your tester on the very end of the thermocouple (the part that attaches to the gas valve). You should read a minimum of 12 milivolts. If you do not read 12 milivolts, your new thermocouple is bad. If you are reading 12 milivolts, screw it back into the gas valve, relight, hold the button for minimum 45 seconds. Release the button. If the pilot goes out immediately, the problem (>99% probability) is with your gas valve.
Answers & Comments
First, I'm assuming you have a residential Gas-Fired Heater or Water Heater that you are having problems with. My answer is based on this assumption.
Most thermocouples require that you hold the button for at least 45 seconds. Try holding the button for 60 seconds prior to releasing it. If this does not work, you can test your new thermocouple if you have a multimeter...preferably one with an alligator clip for your leads. To test your thermocouple, disconnect the end that screws into your gas valve. Set your multimeter to read Milivolts. Put your red lead on the copper line of the thermocouple.....it's easier if you have an alligator clip. With your pilot lit, hold down the button for 45 seconds and continue to hold while you put the black lead of your tester on the very end of the thermocouple (the part that attaches to the gas valve). You should read a minimum of 12 milivolts. If you do not read 12 milivolts, your new thermocouple is bad. If you are reading 12 milivolts, screw it back into the gas valve, relight, hold the button for minimum 45 seconds. Release the button. If the pilot goes out immediately, the problem (>99% probability) is with your gas valve.