I am planning a 4 zone system, fed from storage, with a modulating temp. control valve to supply a constant temp. Also will have a variable speed circulator supplying the 4 zones. They will be piped in parallel. I understand that without balancing valves, some zones will get more flow than others. I am wondering if this matters much since it will just mean that the zone valve will stay open longer for oversupplied zones and close sooner on oversupplied zones, won't it? Would using modulation valves instead of on/off zone valves on each zone be another way to do this instead of a balancing valve and on/off zone valve? Thanks.