Originally Posted by wahoonc
You should have an indicator your regulator that points to the tank in use. The other is empty, close the valve disconnect and take it to be filled.
As far as driving with the fridge on... yes, no, maybe.
If the fridge is completely cooled down and pretty full you can run a good ways before it warms up enough to be a problem. The only issue with running with LP would be during refueling and some tunnels/bridges prohibit it.
I am more prone to run with the furnace on in the winter time that I am to run with the fridge on.
The automatic switch over regulator is pretty standard in todays RVs. Take a look at your regulator, if it has a the lever Aaron is talking about, there should also be an indicator that will change from green to red when a tank has emptied.
If you don't have an automatic change over regulator, it is well worth upgrading to one. The cost will not be much more than buying an indicator for each tank.
I drilled a 2 1/2" hole in the tank cover right at the indicator level and glued a piece of lexan on the inside of the cover. Now it's a simple matter of having a look through the window once a day, when the indicator is showing red, remove the cover, switch the lever to the full tank, close the valve on the empty tank and get it refilled. Replace and repeat.