I'm in the process of installing an indirect DHW tank and want to take this opportunity to clean up the boiler plumbing a tad. The current near-boiler piping has some mistakes (air scoop off an elbow, circulators pumping into the expansion tank, no hydraulic separation, etc), and I am exploring a couple plumbing options.
The house is 1100 square feet, climate zone 5, two stories and two zones of fintube on circulators. Burnham SCG4 boiler derated to 91,000 btu/h in, 78,000 BTU/h out. Down the road I may want to add a small zone of radiant floor to the bathroom (70sf, ~2000 btu heat-loss).
The house is quite small and the utility room is very cramped, but I'm looking for "the right way" to do this, and am willing to pay a little extra. Since I am ripping apart the near-boiler piping, I wonder if I should
a) plan to build in CI boiler protection, and
b) include P/S piping in the way of Caleffi Hydrolink.
I realize that the CI boiler does not need P/S, but I've been impressed with Caleffi's product line (and Idronics!); the Hydrolink appeals to me because it's a very tidy installation for my small space, and it can be easily expanded if I ever add radiant floor in the bathroom. The downside is that it's pricey and possibly makes my system more complicated than it needs to be; I'd need 4 circulators (System, DHW, 2 zones) and one more if I do the bathroom floor down the road. The indirect would go on the system side, not off the Hydrolink.
Question 1: Am I overthinking the design for such a small space? Should I be looking at simpler alternatives?
Question 2: Do I need boiler protection? I think for the current system (fintube only) the answer is probably no. But is it good to have anyway, say, to prevent cold shock after a set back on one zone, and especially if I add that radiant zone in the future? If I end up doing it, would it be better to plumb in a system bypass with the Caleffi ThermoMix now, or should I worry about it when I decide on the radiant zone, and regulate the return water temperature from that zone alone e.g. with an i-series mixing valve?
Thanks for all your time. I've learned a lot reading these forums.