Water Heater Modes of Operation
Although I am not sure about the 22FE model. In most cases they are dual powered running either on propane or electric. If you check the Control panel and it has two switches one marked electric and one gas grouped together then you have dual mode operation. In my case when hooking up to a campground electric service I switch on electric only. When taking showers I then switch on the gas to improve recovery time as both will be heating the water. Even running all the time on gas will not use a lot of propane if you aren't using a lot of hot water.
Hope that helps.