Odd problem

[Robaz]

I have a gas Rheem 40 gallon water heater that has a strange issue. It has been recommended that I replace it but thought I would ask here before I do.

The pilot light will not stay lit. I have replaced the thermocouple twice to assure it is not that. It will come on and stay on but after heating a tank the pilot light goes out. I have to wait a while and light it again. I had a plumber check to make sure everything was working but after he left it did it again after heating a tank. He recommended replacing the unit rather than going to the next step of replacing the gas controller. It is just a weird issue. If I try to relight the pilot soon after it has brought the tank to temperature it won't stay lit but if I wait a while and try again it will stay lit and I can heat another tank.

I was wondering if there might be something I can check or do before I replace the controller or the entire thing. It is a rheem model 22v40f1 40 gallon heater that is 14 years old. Thanks for any input.

 

[havasu]

14 years old? I think you already know the answer.

 

[Rickyman]

It could be the combustion air screens are clogged and it’s starving for air.

 

[Robaz]

It could be the combustion air screens are clogged and it’s starving for air.

I'm curious if you're talking about the combustion holes on the side of the heater. There are no obstructions and it is clear all the way around is there something in there I could check to make all those holes are allowing enough air? I could vacuum all the holes if you think it would be helpful. Thanks.

 

[Robaz]

I just went out and checked all the holes are clear but I vacuumed them out anyway and it still didn't make a difference.

 

[voletl]

Replace the heater.

 

[breplum]

If all the combustion ventilation is clear, and no obstructions at the vent cap on the roof then you have to check for millivolts coming from the thermocouple.
At 14 year, that gas control valve is not worth replacing because the WH is past its useful lifespan anyway, unless you changed anode rod over the years.