Question: “On my natural gas hot water heater, the pilot will light but it will not stay lit. I believe the pilot initially went out because the emergency shut off switch was flipped off. I didn’t notice for a couple of days because I keep the water temp on the low side anyway. I’ve tried several times and the pilot will light but when I let go of the red button, it goes out again. Thanks for your time.”
Answer: In our opinion, you need a thermocouple or if it is a newer water heater there will be a little disc with two wires going to it, this is called a roll out switch, it will have a red reset button in the middle of it – press the reset button and then relight the water heater.  Please note this roll out switch is only on some models.