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Water heater question.


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Neighbor's usual 6 gallon water heater...... it's propane only. Plenty of gas as evidenced as the stove is working AND the fact that the pilot flame lights, and stays on. This tells me the thermo couple is working AND there's gas.


BUT, when turned further on, the main burner does not ignite......




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It is one of the older ones with the manual valve that you turn the control to pilot then on correct??


Check for 12 volts. As I recall the pilot will light without power. Could be lack of 12 volts or a blown fuse on control unit or a bad control unit if power is going to it.

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With the pilot holding, that proves the thermopile is generating power. These older units use a thermopile to generate the power needed to pull in the gas valve, instead of using 12 or 120 volt to open it. Thus, it must be a sticking gas valve. Another, much rarer issue, is the thermopile has been changed out for an incorrect thermocouple. The wrong unit just can't generate enough power to pull open the main gas valve, but will run the pilot just fine.

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It was working this morning, so not the wrong thermopile..... do they go bad?

Yes, they can fail but the symptom of that is that the pilot will go out as soon as you stop holding the knob down in the light position. The reason for the push down position of that knob is to over ride the not yet heated thermal sensor. If it fails you loose the pilot as soon as you release the knob. The thing that I'd suspect at this point is the thermostatic control. That is what tells the gas valve to open and send propane to the burner where it will then ignite from the burning pilot.That is a part of the gas control valve. Here is a link to a manual that should help you to trouble shoot it.

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Oscar, you say "knob turns no pushing" that's one typical method used on the older non electric manual pilot light systems. Some you had to turn to "Pilot" then push in, others turn to Pilot then turn a tad further against slight spring return pressure, and light the pilot, then continue to hold until the thermocouple heated up. Once its hot enough you can release the spring pressure (or stop hold down) and IFFFFFFFFFFF the thermocouple is good, it will remain lit, otherwise it will go out. If yours stay lit once the spring pressure is released I DONT THINK YOUR THERMOCOUPLE IS THE PROBLEM.


However to answer your direct question YES they do go bad and I've seen far more T couple problems then the gas valve and thermostat, but staying lit once released tells me your t couple is okay.


Age or corrosion or moisture or sticking etc etc can be at fault concerning the gas valve and thermostat, but I haven't had the nerve to disassemble and tear into one to try and "fix" it. The assembly isn't that expensive if yours is at fault and cant be easily repaired.


John T

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