It takes about 22 KW of electric in a electric heater to equal 1 gallon of propane. So for the propane water heater, it is like this.
22 KW X 13 cents = $2.86 So if propane is easy to get and less than $2.90, then run on gas and buy propane. If more than $3, running on electric is less expensive. (same for the refrigerator).
If you are running electric heaters (say when it is below 40F outside, or if your RV did not have a heat pump, the above also applies.
However above 40F, the heat pump is "Transferrring " heat from outside to inside. They can do this at the rate of 13,500 Btu's per hour for only about 1.3 KW per 13,500 Btu's. Or 10 Btu's per hour. The electric heater is 3,400 Btu's per KW.
So to collect 80,000 Btu's with a heat pump would require about 8 KW or $1.04 in your case. So much less than running a electric heater or propane.
When it is less than 40F outside, then the heat pump thermostat will change over to the propane furnace. So I would have a couple of 1500 watt electric heaters. The portable heaters that I have have a thermostat, high output and low 800 watt output. I can run two heaters on low heat, or one on high and the other on low.
Good luck,
Fred.
