this coal boiler uses Johnson controls controller relays, A350 module its high/low set for boiler temp, controls underdraft air door opening closing. next module is Y350 power module for 120V connects to all modules, 3rd module is S350 module for overfire control, use it to run zone1 845a relay when i need to dump excessive heat from boiler. theres no extra C1/C2 terminals in any modules.
Thats why i was thinking of elimanating all tthe 845a relays, use the 504exp as main control relay for everything, and PC702-1 plug in module for it to stage circulators off of instaed of oil burner head or coal air draft door. And still be able to wire S350 coal module to 504exp for #1 zone to still be used as dump zone, and when it activates cola boiler circ will come on also, if theres no other zones calling for heat, and if there was there wouldn't be an over fire anyway. thats where the cube relay comes into use, wire it for noraml open to coal boiler circ, so when satge module of 504exp calls for oil boiler to maintain manifold temp at zone manifold and switches on oil boiler circulator, it switches coal circ off until manifold temp is reached and switches back to coal boiler only for heat source. its programable for manifold temp range for switching from one boiler to the other by zone manifold water temp .
Rob R. wrote:
wilder11354 wrote:i want coals primary circulator to only run when there is a heat demand by one of the 4 zones.
That is simple enough, run the circulator off the C1/C2 terminals in the triple aquastat on the coal boiler. You will also need to connect the end switches of the 845A relays to the TT terminals in the same aquastat.
As for the oil boiler, I am not sure how you bring it online. Do you turn it on manually?