How to tell if hot water heater runs off gas or electric

korbe wrote:

RoyF wrote:
The hot water heater on propane will make a "roar" and there will be hot exhaust gas coming from the heater on the outside of your class C.

And while outside noticing the roar, and feeling the heat, go ahead and open the outside door and take a peak and see how its heating. Part of the learning process. On shore power, an electrical heating element inside the tank is heating the water (if switched). Two completely different processes.