In a haste to get the boiler up and running at this house a couple years ago, I just did one big loop from my boiler to the furnace to the water heater and back to the boiler. It works, but I want to expand on the system in the future. At my old house, I had Earth Lee build two headers out of black iron that were 1-1/4" bodies with two 1" ports and five 3/4" ports. Both ends are open on both headers. I plumbed them up so one was an inlet and one was an outlet and the devices between were what transferred water from inlet to outlet.
At this house, I want to do a manifold system for easy expansion as I add to the system. I was thinking that I'd take those two headers and couple them together end to end so I have one long header with a 1-1/4" body and four 1" ports and ten 3/4" ports. I'd put a separately controlled Taco 007 pump on each loop I want and use the upstream ports for supply and downstream for return, matching port sizes of course. What do you think of that?