I figured hvac was the most accurate place to post this dealing with a gas valve. I'm working on an AOSmith water heater. Model number GCV 40 100.
Customer complaint is he has to keep relighting the pilot 2-3 times a day or more. I saw the pilot go out once while there but cannot duplicate the problem. He said someone replaced the burner assembly approximately 8 months or so ago. thinking the pilot assembly may be getting flaky I wanted to try something. I disconnected the thermocouple and put my meter on it. I installed a new thermocouple outside the unit and put my heat gun to it. I lit the pilot and then turned on the heater. I read high 28 low 29 millivolts the whole time the thing was running. I started off on the lowest temperature and worked all the way up to the highest temp turning it down several times and turning it back up just to make the valve go off and on. when the gas valve was off it would drop down to about 26 millivolts, then go right back up to 28-29 when the burner turned on. The way I see it I can sell them a gas valve, a pilot/burner assembly, or a new water heater. It's almost sixteen years old but no signs of leaking. I want to fix this for them but not sure which way to go not being able to catch it in the act. I know there is a possibility that the burner they put in may have been bad. but the gas valve could be flaking out too. Has anyone ran into this before? The air intake screen at the bottom is clean and part of the anti flashback honeycomb crap at the bottom is broke away so it has to be getting plenty of air.