Normal. Heaters need to maintain the temperature of the water in the tank.
Heat losses are the reason that it comes on by itself.
"buffy92027" wrote in message
...
I live in a mobilehome and I have a 6 month old GAS water heater
outside. I thought the water heater ONLY comes on when you use the HOT
water. I heard it come on this morning at 5:00 AM(it was really cold
outside) do not know if that makes a difference. It stayed on for 15
minutes. Is this normal? thanks