Why have the first tank run out at 3 am, and have to go out in the rain in your PJs to open the other tank????
The auto switch-over will do that if you leave both tanks open. That's what it is for. Had that in the 5er we had.
In the morning, doing your "morning rounds" of the RV, one day, you will see the indicator is red. That means go get the first tank refilled. DO NOT switch the lever over yet!!!! Leave it pointing at the empty tank.
(Or else it will go green and you will think next look that all is well--until it goes red and now both tanks are empty. Oops!)
Once the refill is done, open that tank too and now switch over to the tank in use, and it goes green.
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Our C has an "extra" light-set in the "monitor" over the stove to indicate how full the propane tank is. There is another hard to see gauge on the tank itself. Routine is to notice when low on propane, go get some more.
Around here there is a shortage of places that do MH tanks, so if near one, and getting down, I fill up whether need it or not, in case I don't get back near a place that does tanks. (Lots of places do cylinders, but that is no use) It is like you need "local knowledge" where to get propane for the C. I pity any tourists! :(