2 pipe hot water loupe design

Scott Green

circulator will be running continuously. Each room will have machanical thermastat on radiation. When the thermastat calls for heat , it opens , letting hot water flow through the radiation , then into the second pipe being used for cooler return water. It won't dump back into the original hot water line , cooling the hot water down. My question is: what would be the best set-up for the flow of water? I'm guessing a devirter elbow on the main hot water line. The machanical thermastat at top of "T" at radiation. And one size smaller pipe after thermastat , looping over radiation , bypassing the radiation , and going back into main hot water line. This is going to be a new installation useing a coal fired stoker boiler. What do you think? Looking forward to opinions / ideas. I'm still in the reserch stage of this project. Thanks , Scott