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primary/secondary pumps (how to wire the primary pump)

I'm setting up a boiler with primary/ secondary piping. 3 zones. 2 radiant and an indirect. My question is how do i wire the circ on the primary loop to run whenever any of the secondary pumps come on? I'm using a taco sr504 expandible 4 zone switching relay with priority (If i can).


  • hydronicsmike
    hydronicsmike Member Posts: 855
    X-X End Switch

    Could use the X-X End Switch on the 504 to run this pump. If you also need a dry-contact close for your boiler, then you could have a DPDT Relay energized by the X-X terminals on 504. one N/O contact is used to switch power to the pump and the other can provide a call for heat to a boiler or reset control.

    Hope this helps. If not, call the guys at TACO, they are great!!

  • carol_3
    carol_3 Member Posts: 397

    thanks, hydronicsmike
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