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Primary/secondary/tertiary pump control?
When the indirect calls for heat the boiler primary circulator and the indirect (secondary) circulator must be switched on.
You say the indirect is across the primary (boiler) loop. In that case, the boiler loop circulator need not be switched on as the circulator for the indirect can handle the required flow both for the boiler and the indirect. That circulator should probably be the same size as the boiler circulator. Unless you have some unusual circumstances, you do not need closely-separated Ts to connect to the indirect. I assume when you run the indirect, you do not run the heating zones; i.e., that you give priority to the indirect.
N.B.: I am a homeowner who has his boiler plumbed about the same as yours, but no tertiary loops.
In summary, when the indirect calls for heat, only the indirect circulator runs.
When a heating zone calls for heat, the boiler circulator and the zone circulator for the heating zone run. Sometimes, if both my heating zones call for heat, the boiler circulator and both heating zone circulators run.0
Diagram or photos
A diagram or photos will help. I'm not sure I'm understanding exactly. If the indirect is connected to the boiler loop with close tees than the boiler circ and indirect circ will run on a call for DHW. To get away from that you need to connect the indirect so that circ will move the required GPM thru the HX withoujt the boiler circ running. This is also assuming DHW priority. If all your heat zones have circs and are hooked into the secondary with close tees, and all are running won't the farthest downstream zone receive cooler water? I have what they call the Moose Antler setup. My boiler loop is hooked into the Moose Antler with close tees, all my heating zone circs and DHW circ pull the same temp water off and return it back to the loop. The boiler just supplies hot water to the loop thru the close tees. If I was doing it over I would not have my DHW as just another zone. I would do it as I decribed previously. No matter what type of call I have, heat or DHW reqiure at leastr 2 circs to run. My boiler loop, close tees and supply piping is all 1 1/4" and pretty short and compact so not that much wasted heat. Others will better ideas and descriptions.0
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