Because of a water leak from above the basement, with water dripping near wiring in the basement, I decided to shut off the circuit breaker for all wiring feeding near my water heater until the plumber shows up (hopefully tomorrow). My question is about the water heater, though. I do not see any electrical wiring going to the water heater. I never noticed this before, but now I'm wondering: How can this be? Is there no electricity required for my water heater? I'm totally mystified. (A.O.Smith Model FCGL-40)

when i look up that number (A.O.Smith Model FCGL-40) i come up with a gas water heater.
no electric needed unles it has a power vent.

Yes Packy. It is a gas water heater. I guess I just don't understand how it works, with respect to triggering it's thermocouple (or whatever). But, I'm interpreting your answer to tell me I don't need to worry about my next hot shower. GOD! I hope that's right!

The thermocouple generates enough current to hold the gas valve open. No external power needed.

The thermocouple generates electricity when the pilot flame heats it up. This small amount of voltage/current is all that's needed to operate the gas thermostat valve.

Thanks, George, for your response. I'm somewhat less mystified, now. Also, much relieved.

Thank you, Steve, for your explanation. I'm feeling much better about the situation, knowing this, now. Good to know I won't be showerless, and all stinky tomorrow!



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An interesting tidbit. Thermocouples generate low voltage (30mv) and current (700ma short circuit). This is not enough to pull open the main gas valve, which is why the valve has to be manually opened by depressing the red button.It takes less current to hold the valve open than to open it from closed position.

thats like me getting up in the morning.
lots of effort but once im up (and had coffee) im OK.