Our New TT (May-2020) has a Electric/Propane water heater that has become very noisy lately. If only it were not right next to the bed. But it is and the 2' proximity with a very thin wall for seperat...
Our water heater " suburban I believe " has an electric on-off switch at the WH itself, another electric on-off switch at the control panel and separate Propane switch. I've not seen this configuration before.
Regarding the OP's concern. We've yet to use Propane to heat water when hooked up to electricity.....family of 5 until kids moved out.