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Connecting Taco Controls and Nest Thermostats

HeatingHelp.com Member, Moderator, Administrator Posts: 7
Here are instruction sheets for Nest to Taco ZVC with 3-wire application, Nest to Taco ZVC with 2-wire application, Nest to Taco SR with 3-wire application, and Nest to Taco SR with 2-wire application.


  • Dave H_2
    Dave H_2 Member Posts: 554
    Erin and all,
    We have also spoken with Nest recently in regards to wiring and they suggest using the resistor wiring as shown but they do suggest using a 220 ohm, 5 watt resistor instead of the 1,000 ohm, 0.5 watt resistor we supply with the controllers.

    Dave H.
    Dave H
  • SteveSan
    SteveSan Member Posts: 234
    Also make sure to pre-charge the Nest so that the battery is at 100% before wiring to the ZVC or SR controls.
  • Erin Holohan Haskell
    Erin Holohan Haskell Member, Moderator, Administrator Posts: 2,283
    Thanks, @Dave H_2 and @SteveSan!
  • PEvans
    PEvans Member Posts: 116
    Do the Taco ZVCs apply power to close the valves, or are they assumed to be self-closing? Said differently, does the Nest connect power from Rh to W1and C respectively when calling and not calling for heat?