Originally Posted by tnchuck100
If you are running on a generator you do not want the water heater running on electric. It is best that YOU make the determination how it is operated.
The refrigerator is a special situation. It is automatic so your food does not spoil due to a 110V power failure.
x2. To keep your refer cold while traveling, you may want to run it on propane, since the electric setting won't work when the rig is not plugged into shore power. The "Auto" setting takes care of the changeover "automatically" when you plug in at your destination. Chances are, you don't need hot water while traveling (or when your tanks are empty and you're not connected to "city water"). Having switches forces you to make a conscious decision to turn both electric & propane off
assuring less chance of trying to heat an empty water heater - and burning out the unit.
Also, (generally speaking) electricity is less expensive than propane, so it's less expensive to run both on electricity - when it's available. At state park campgrounds (where I'm paying for electricity as part of my CG fee), I'll typically leave both refer and WH on electric all the time. But when I'm camping long-term at a full hook-up facility and have to pay for metered electric, I only turn on the water heater about 15-20 minutes before a shower or doing dishes. When you're boon-docking, you still want hot water, so there's the option on your control panel to run it off propane.
Finally: I don't know if it makes a difference or not, but on nights when the temps are going to drop below freezing, I'll turn the water heater on (elect) for 1/2 hour or so, then turn it off before going to bed. The water in the WH will stay warm until morning - preventing the tank from freezing. The water heater is, after all, directly exposed to the outside. Like I said, I don't know if it makes a difference or not, but I figure "an ounce of prevention . . . "