Bad title. I meant gas water heater.

Sometimes there is hot water and sometimes there is not. No pattern to it.

When we don't have hot water, I will turn the water heater off and back on. It will begin to run, the electric pilot will light, and the flame will light. Sometimes it will stay on and it's fine. Most of the time the flame will just go out anywhere from 2 to 10 seconds after it is lit. I just hit the switch again and it will do the same thing. Sometimes I only have to hit the switch once to have the flame stay on but sometimes it will be up to 4 times before the flame decides to stay on and heat the water.

What would be the problem? The water heater itself is working and heats the water just fine but something is not reading right.

Thanks,

" electric water heater won't stay on" They you say "flame will light". What is it- an electric or gas heater? Sounds like you have a bad thermocouple if it is gas.

Sorry, you're right. It is a gas water heater. I meant to say the ignition is electric or automatic.

So it is a bad thermocouple? Where is that located?

Thanks,

It could be 2 things. The thermocouple is the small wire like line that runs from the gas valve to the flame. It is a safety device designed to shut off the gas valve if it doesn't generate enough microvolts to keep the valve open. The pilot flame impinges on it. Not particularly hard to change but space is usually limited . Google:"changing a pilot thermocouple". Another possibility is dirt in the pilot line. There is a very small orifice for the pilot light and even a small speck of dirt in the supply line can clog it. Just be careful working around gas and if you can't get help or are hesitant, get a plumber to do the work. What is a little strange is that it comes and goes. Usually a thermocouple goes bad and that's it.

Is there a way to test the thermocouple? It's a pretty spendy part. Thanks

Unless you have a specificly designed thermocouple that only fits your model, they are universal and cost about $10-15. Some of the newer models with full electronic ignition are $25. If your Volt Ohmmeter can read millivolts you can test them. You need to remove it, place it is a small burner flame and measure the millivolts. Most HW thermocouples run about 30 millivolts. Measuring resistance is not always the best way since a shorted t'couple can read the same as a new one, <2-3 ohms.

This is the one that I can find. I have an AO Smith model FPSH 40260. The thermocouple (part 183267) is included in this entire assembly which costs over $100. Is this the right or am I looking at the wrong part?

That does look part specific but I would try one more thing. Since it is erratic, make sure the pilot flame directly hits the part connected to the yellow wire, that appears to be the thermocouple. I have a new house-3 yrs- with a Rheem HW heater. I always buy an extra thermocouple and mine was $10. If all else fails, Google your model and look for parts online . $100 seems pretty pricey.