enblethen wrote:
Make and model of water heater would help.
Check the flame sensor to insure it is in the center of the flame and adjusted correctly.
Your circuit board could be bad! I will wait for make and model!
Propane would run off batteries when not connected to shore power.
Checking images, i believe it is a Suburban heater.
My theory - heater doesn't seem to recognize the flame is going. Will it stop the gas in conjunction with the completion of the ignition cycle ? If so, how is it sensed ? I don't see anything in the burner path to identify the flame is burning.