I have a 30 gallon Rheem hot water heater that is fueled by propane. After 3 years of flawless operation, the pilot light will occasionally go out. It does not go out every time. I have replaced the thermocoupler, and the proplem pesisits. The gas line from the controller to the pilot light is clear with no obstructions. The pilot light is more than adequate in size and the tip of the thermocoupler is directly in the flame of the pilot light. Is it the controller?

The Rheem water heater has vents on the side that alow fresh air to get to the burner. After this air enters the side it then is sucked up through a slitted screen directly in the bottom of the heater, and below the burner. This is meant to be an anti-explosion device in case explosive vapors were to get into the air from a spillage of gasolene or some other substance. After a time these slits get stopped up with lint and dust and it needs to be cleaned in some way. One way is to use a shop vac and reverse the flow of the vac to blow, disconnect the vent pipe at the top of the heater, put the hose in there, stuff some rags around it and turn the vac on and try to blow the lint and dust out.

If this does not work give me an answer and I will tell you another thing to try.