QuestionI have A 1999 thor tahoe with atwood gas hot water I can lite the heater it will run for 15 to 20 seconds and shut off I replaced thermo cuppler.
Answerpossible spiders in gas valve, possible you are low on propane
I know you've changed the thermocouple, and it should be good, but if the pilot LIGHT goes out while the main burner is on, the thermocouple will cool, and shut off the main burner.
I believe your problem could be in either the pilot light intensity, or direction could also be a problem when the main burner is on. i.e. the draft from the main burner drawing the pilot light flame away from the thermocouple. If the thermocouple is getting too cool, it would shut off both the pilot and the main burner at the same time.
1) Check gas pressure. should have 14" WC (minimum is 11" I believe)
2) Remove pilot assembly from burner tube and see if pilot stays lit while main burner runs. Main burner could pull pilot away from thermocouple and shut off gas.
If So:
3) Take pliers and bend pilot and thermocouple closer to each other, so pilot flame would engulf thermocouple. (just move them about 1/4" closer to each other).
4) Reinstall assembly into burner tube, further away from main burner to reduce pull on pilot.
Now it ahould work fine. The pilot is further away from the burner draft, and is now closer to the thermocouple, which stays red hot from the pilot.
I heard of a similar problem. Once the water was hot the pilot went out. Repalced regulator and WH burner and control. The WH pilot still would not stay lit. Blew out the gas line to the WH and found a well preserved moth that had been in the copper tubung. Problem solved
