My method is to keep the looping as simple as possible, which means one zone per level and the tank is good because it is a big mixing chamber but most of this is about control and measuring the temps in the right places.
Michaels system, above, is very traditional and If his insulation levels are reasonable he could be turning down the mix temp and boiler temp by +20F, especially given his location. This is why I like outdoor control on boilers AND mixing valves. There are times when a floor heat system only needs 75F water. Of course, during most of those times, the passive can supply redistributed to the colder parts of the house. Solar hot water can help to charge the tank as well.
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