Avoid the American Water Heater Energy Smart water heaters...
They reinvented the wheel and rather than commonly available thermostats they use thermistors and a circuit board that has to be ordered.
Have it go out on a Friday before a holiday weekend and you'll be able to order it on Tuesday morning so you might see the parts delivered on Friday...
Just another time when American makes its customers wait too long to have hot water in their house...
They do that often...
Habib will explain it on their help line....