I install tankless heaters on residetial homes quite frequently. The ones for campers operate on propane only. As long as you have propane (and small amount of power) you have hot water, they never run out. The are much more effecent than standard water heaters, BUT lets say your camping and always park at a campgroud. If you always have your standard water heater on electric with the gas option off (and not paying for metered electric) then your getting your hot water at no cost. Now if you turn the gas option on too ONLY when showering so you get more hot water befor running out then the tankless may save you some propain. If you are boondoking or frequintly have the gas option turned on then the tankless will defently save you propain. I think just knowing you will not run out of hot water makes me a fan.