Nest Thermostat compatibility with Taco 571 zone valve

[jammy1954]

I have a gas-fired hot water system with 4 zones. The zones utilize Taco 571 zone valves. There is a Taco SR501 that controls the boiler and circulator, so the thermostats are wired directly to the zone valves, not through a Taco controller. 

I want to replace one legacy thermostat with a Nest 2020 thermostat (mirror face). I have R, C & W wires for that zone. 

I have been told that an isolation relay will be required between the Nest and the 571 because the 571 will intermittently open the R-W circuit to prevent overheating the wax in its first stage.  Is this correct, or will the Nest work if directly connected without the relay?

[Jeran]

Hey there jammy1954,

I am sorry about the late response on this thread, thank you for being patient! Were you able to find the answer to your zoned system question? If not, I'd be happy to help out. First, I would recommend that you check out this article on zoned system compatibility with Nest Thermostats. It mentions that usually compatible with zoned systems that use multiple thermostats, including zoned systems with dampers. However, some zoned systems that require thermostat damper control aren’t compatible with Nest thermostats, while other zoned systems may need a C or common wire, or the Nest Power Connector, to be compatible.

I hope that helps you out, and if you had any more questions or concerns, please let me know!

Best regards,
Jeran
 

[Ryan_G]

Hey everyone,

I'd like to jump in here and check if you've seen Jeran's response. Let us know if you need more help by replying to this thread.

Thank you for your help, Jeran.

Regards,
Ryan 
 

[Ryan_G]

Hey there,

Thanks for being here in the Google Nest Community. 

I'd like to bump in here and make sure that you’ve seen our response.
Please let us know if you have any other questions or concerns as I will be locking this thread in 24 hours.

Have a great day.

Best regards,
Ryan