[quote="Boots"]If one were to use a "direct return" piping system, where each "circuit" operated independently (each a different zone with its own circulator, thermostat etc..), Would "balancing" one zone vs. another be unnecessary (all are dissimilar btu requirements)?quote]IF
each of the zones are exactly the same in pipe size - length of runs - radiation installed - and each load served is exactly the same = no
do you qualify on all that?
[quote="Boots"]Am I correct in my understanding that Balancing a system is to achieve even heat in each part of a single zone (so that you do not have some hot rooms and some cold)? quote]
Room [ hot and cold] is [first] controlled by the zone thermostat --- then if the zone has some / all / or any of the differences I mentioned above - well sometimes / usually / often --- those differences can be compensated for.
if the system is designed correctly from the start then each zone [and area in each zone] has the correct radiation and correct energy flow to support it - This is varied by the outdoor reset control to adjust for seasonal/ daily load differences - its balanced because it was designed to be.
spend a little time herehttp://www.heatinghelp.com/article/334/ ... eating-FAQ
The correct place to do the radiation balancing is on the paper you engineered and designed from calculations, not a guess. BUT often the lowest bidder didn't have a sharp pencil - he usually wasn't even the sharpest tool in the shed!