Hello Gentlemen Im trying to split my one zone hydronic system into 3 zones.2nd floor consists of 3

jerseyfitter

pieces of CI baseboard.These are piped to basement individually ,3 3/4 supplies and 3 returns.What type of system would you suggest? 1pipe,2 pipe reverse return ect. The other zones are series loops.

kcopp

Sounds like its a mono flow system. Be careful here they can be a nightmare if not piped correct. Also how much radiation per zone? Micro zoning can be a problem and cause the boiler to short cycle. Don't use wild temp differences between the zones.
I would pipe the 2nd fl to a manifold set up Keeps it simple and balances the flow to each radiator.
I would certainly use zone valves vs. circulators.
What are you using for a boiler?

jerseyfitter

older slantfin 90 hw boiler