So I got into an argument with my installer, who is kind of young... We are installing radiator hot water heat on a two story house, there's an upper floor manifold, and a lower floor manifold, a tstat on each floor operating the circulator on each manifold. I like to keep the heating system as simple as possible. All the radiators are plumbed home run, except one, and that's in a long room where we have two radiators that will share a loop. My installer wants to plumb these two radiators in series. I want to plumb them two pipe reverse return with a diverter tee. He says we won't be able to balance the manifolds properly doing it this way because there will be too much resistance introduced by the diverter tee, and we'll have to dial down all the other loops. I can't see why this would be the case, seems like roughly the same resistance either way, and my way both radiators get equally hot water.... Who's right, or more likely, why are we both wrong?