For three years now I have been dealing with an unbalanced monoflow system heating the upstairs of my house. The original installer ran wall-to-wall fine tube baseboard in the rooms with no regard to heat loss, and installed the thermostat in the hallway right at the top of the stairs. This caused a few problems. 1. The temperature downstairs directly impacts the operation of the upstairs thermostat. 2. The monoflow tee's were installed only about 6" apart, and barely created any flow through the long runs of baseboard. I cut the entire monoflow system out, put the bathroom on its own zone, and put the rest of the bedrooms on a manifold with pex tubing. I am now able to throttle the flow and balance the heat room to room, and to top it off....I installed a wireless thermostat in the center bedroom. I also added a few valves and a boiler drain to allow me to purge each radiator loop from the basement...no more bleeding!