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Millivolt aquastat L8148J with Taco sr503-exp-4

HydroNiCKHydroNiCK Member Posts: 104
How do I/can I use a Taco sr503-exp-4 with an L8148j aquastat? Can I wire XX to TT TV on the aquastat? I want to control a primary pump and two additional circulators on the secondary piping.


  • IronmanIronman Member Posts: 5,807
    Bob Boan

    You can choose to do what you want, but you cannot choose the consequences.
  • HydroNiCKHydroNiCK Member Posts: 104
    Can I leave the primary circulator on aquastat's c c and have it energized whenever a sr503 turns on if I didn't use sr503 primary pump ON setting. In other words primary circulator wired to aquastat in parallel to secondary circulator wired to the taco switching relay?
  • HVACNUTHVACNUT Member Posts: 3,516
    Yes. XX on the SR504 to TT on the aquastat. Any zone that energizes on the 503 will close XX, initiating a call to the aquastat and powering B1 and C1.
    My setup is similar, but not millivolt.
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