The Watts(r) recirculating system I'm about to install required an additional valve (or valves) if I have a branched hot water system. How can tell if I have a branched system? The whole system is enclosed within the walls.

All water systems have a main that feeds pressure to each branch. All systems have this. A 1/2" branch can furnish water to no more then three fixtures. One branch feeds the bathroom, one branch feeds the kitchen, etc. And so on. Follow the directions that Watts gives you. Good luck, Tom