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Aquastat and ZVC

I currently have a system with a Honeywell L8148E Aquastat hooked up to it. I'm looking to hook up a Taco 404-4 ZVC to the system to control the zones. My question is, how do I hook up the pump? Will the Aquastat still function if the pump is not wired to it (wired to the ZVC instead)? Thanks.


  • rick in Alaska
    rick in Alaska Member Posts: 1,458
    Use the tt contacts on the Taco control to run the boiler instead of the end switches on the zones. Keep the pump wired to the aquastat as it is right now. Assuming of course you are using end switches to control the boiler and pump, and the pump is wired to the aquastat.
    This way when the thermostats open the zones, the Taco control will close a dry contact and fire the boiler and pump.
  • Dave H_2
    Dave H_2 Member Posts: 558
    do you have one or two circulators in your system?

    take a look at the attached wiring diagram

    Dave H
  • phaiel
    phaiel Member Posts: 2
    Just one circulator
  • Solid_Fuel_Man
    Solid_Fuel_Man Member Posts: 2,646
    Yes the aquastat will still function. The Taco zvc has two sets of dry contact outputs. Use one to the TT on the boiler and the other set to run the system circulator.

    Serving Northern Maine HVAC & Controls. I burn wood, it smells good!