Well the time has come for me to correctly re plumb the indoor side of my heat system. Back in 07 when I had no idea what I was doing and how complex my house would become, I simply ran my plate exchanger first in series with my forced air hx. Simple, 1 pump on back of the boiler and 2 hx's. Now I am up to 4 hx with the future plans of one more. You can imagine what the head loss is and what my return temps are. Believe it or not it still actually works quite well since there are rarely more than 2 hx's calling for heat at one time. Still, I am currently up to 4 now with the plans for 1 more for sure, and who knows where I go from there. Back in 07 if you would have told me how much I like all this stuff and how it has almost become a hobby I would have laughed.
I've got a pretty good idea how I want to do it, I just need to know all the correct names of the components. I plan on converting to a primary secondary loop. On the secondary loop each hx will be a separate zone, with each zone controlled with a zone valve. A single pump will take care of the secondary. That is where I get a little lost. What exactly do I need at each hx to tell its zone valve to open and how does that zone valve tell the secondary loop pump to turn on or off. I know there are relays and pump controls but I need to know what they are called and how they work and are wired.