I'm curious about something. When you say "home run system" do you mean that each convector is run to the boiler and that's where the series connections are made? Because if that's what it means, then that is a lot of piping to pump hot water through, isn't it? Wouldn't it be better to connect all of the convectors in each zone with as little piping as you can?
I'm just trying to understand what you mean so if I'm off base here, please accept my apology.