OK.......
Pull the pilot/thermocouple assembly out of burner tube
Clean off thermocouple will some emery cloth
Reassemble
Turn knob to 'pilot' and light pilot
Check pilot flame and that it is engulfing the thermocouple
Wait until pilot flame is stable and stays on
Then turn to ON
IF pilot flame will not stay lit then the thermocouple is bad or the ECO has tripped (one shot high temp t-stat----internal of gas control)
IF ECO has tripped.....new gas control valve.
Yours is a 'Jade Control'
Here is a service manual that includes your Atwood pilot water heater...pg. 8-11
LINK
