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Can I use taco valve 571 common wire for nest c wire?

Community Member

I have a house/furnace built in the 1980s.  We have only red and white wires connected to thermostat.  Thankfully they ran a third wire from the taco valves up to all three thermostats.   Is it as easy as connecting the third wire to the c wire connect on nest and to the common port (second) on the taco valve?


Platinum Product Expert
Platinum Product Expert


Theoretically, you should be able to connect the C terminal of the thermostat to terminal 2 on the valve, the W terminal to terminal 1, and the R terminal to the 24Vac transformer.

Figure C shows the wiring that I am referring to.

Heat Motor Zone Valves 


To ensure that I see your reply, please tag me using @Patrick_Caezza

Yes, that worked

Community Specialist
Community Specialist

Hi folks,


@Robertbiron, thanks for the update and I'm glad that the issue is now resolved. Please let us know if you have further questions or concerns. Otherwise, I'll be locking this thread after  24 hours. 


I appreciate your help, @Patrick_Caezza and Jake. 




Community Specialist
Community Specialist

Hey there,


Thanks for the helpful reply Patrick_Caezza.


I wanted to check in and see if you managed to see Patrick_Caezza's post. Please let me know if you have any questions from here. I would be happy to assist, and make sure you are good to go.

Best regards,