[Carl n Susan]

Yes the change over valve will switch automatically to the other tank when the current one is empty. You do need to look periodically to see if the indicator has turned from green (current tank) to red (backup tank being used). Turn the lever to point to the now "current" tank (i.e. the one with propane) and the indicator will go back to green. Turn off the empty tank, remove and re-fill it, put it back and open the valve. You are now prepared for the next cycle.

The good news is if you run out in the middle of the night, when the temps are below freezing, you keep on truckin' without a trip outside in your skivvies to flip the lever.