Most of the water heaters work this way: The switch in the cabin is for the propane. The switch outside the trailer, on the face of the actual heater, is for the electric. Make sure you have water in that tank before you turn on a heater or your heater is toast. If you have a winterizing by-pass, you will need to clear the trailer of anti-freeze, then open the bypass valves and fill the tank with water.
2012 F150 FX4 Ecoboost, 2016 Surveyor 274BHS
2003 Yamaha FJR1300, Demco Premiere Slider
1969 John Deere 1020, 1940 Ford 9N, 1948 Ford 8N
Jonsered 535, Can of WD-40, Duct Tape
Red Green coffee mugs