Connecting Taco Controls and Nest Thermostats

HeatingHelp.com

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

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.

SteveSan

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

Thanks, @Dave H_2 and @SteveSan!

PEvans

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?