[rames14]

Casa -
There is a selector switch on top by the regulator. Whichever tank that is pointing to is the tank that is used first. When that tank is empty, it will switch over to the other tank. However, it will not show the correct propane level until you flip the selector to the new tank. I have never done it, but you should be able to change out the empty tank as long as the switch points to the full tank. We do it the old fashioned way - one tank turned on and use from it, and then turn it off and refill. More than one cold night I've been seen running outside in the cold to turn the other tank on - but I always know I have another tank to use.