Auto change over regulators are nice.......swaps from in service tank when empty to other tank without doing anything.
BUT one must check the indicator to know when tanks have swapped.
Green indicator will change to Red when in service tank goes empty.....then swap lever to other tank and Red indicator will go Green.
Problem is 'when' did it swap.......yesterday, last week etc.
IF one does not check indicator routinely then one may find themselves with 2 empty tanks.
Even with an auto change-over we keep one tank valved out so that when the in service tank goes empty we know it.......valve in other tank, change indicator lever and get empty tank refilled.
Propane usage varies a lot!
We have had to refill 30# every other day in really cold weather and have gone 6 weeks straight on one tank. Just depends on heater usage.
Hate finding out both tanks are empty :B