Manifold and hot water loop

Tristan

This is my first post on the Wall. I removed the very unattractive hot water baseboard in my house and wanted to instal old cast iron radiators. My idea, as I've seen it where I come from in Europe, is to put on every single radiator a Danfoss thermostatic valve that would regulate the heat in every room. The  system would be designed around 2 manifolds (feed and return lines) and every radiators would be individually fed. My water circulator would be always running but only feeding the radiators when the thermostatic valves ask for it. How do you think I can create a loop that would keep water circulating only between circulator and furnace when radiators do not need heat? What kind of thermostat on that loop should I use? Do I have to instal a shut-off valve that I would keep slightly open to create water resistance , thus not interfering with the flow of water to the radiator when needed?

I hope soeone can help me, if needed I can also post a drawing. Thanks