Will Nest work with Honeywell HZ311 and no common wire?

[waf]

When I upgraded my HVAC a few years ago, my contractor installed a Honeywell HZ311 Controller, single stage heat and cooling. The system has three dampers with a zone controlling each of the 3 different sections of my house. Because my home has older wiring with no common wire,  my contractor installed three separate thermostats (Honeywell Battery Powered). He said there was no way a Nest would work without a common wire.

I am now reading that in some cases a common wire is no longer required for Nest to function. How would I be able to tell this before I purchase three new thermostats?

Thermostat 1 has Y, G, W & R

Thermostats 2 & 3 have Y, W & R

[moralesvicente]

Hello waf, 

Thanks for reaching out to the Google Nest Community Forum. I understand you have some concerns regarding whether the Nest Thermostat works with your wiring configuration because it doesn't have a common c wire. So don't worry; I'll be more than happy to help.

Nest thermostats are built to minimize power consumption and typically draw power from your existing heating and cooling system wiring. In some cases, you might need to install a common wire (C-wire) or use a Nest Power Connector to ensure your system works correctly with the thermostat. For your reference, here's an article: Learn about the common or C wire. 

Regarding the wiring system, it is compatible with the different models of devices that we offer. To get more information, check out this tool: Compatibility Checker. 

Please let me know if these suggestions were helpful. 

Best regards,

Daniel

[waf]

Hi Daniel,

The online documentation is a bit confusing and ambiguous. Given that both Y, G, W & R as well as Y, W & R return the same results from the Compatibility Checker, does this mean that the model simply called the "Nest Thermostat" is most likely to work without a common wire? Or are all Nest thermostats now designed to work without a common, and it is only "in some cases" where a common is required? If so, what would be some examples where a common is required?

Regards,

Walt

[moralesvicente]

hello waf, 

Thank you so much for keeping me updated. Let me explain to you more information; the compatibility checker generally suggests that Nest Thermostats 3rd and 4th generation are likely compatible with your system without needing a C-wire. However, the simple Nest Thermostat (the 2nd option listed in the compatibility section) usually requires a C-wire.

If you experience power issues or the thermostat battery drains frequently, installing a C-wire might be necessary for any of the Nest Thermostat models.

Let me know if you have any other questions. 

Best regards,

Daniel 

[waf]

Hi Daniel,

Thanks for that answer. I strongly suggest that Google update their Nest Thermostat C-wire documentation to make it much clearer on these points.

[moralesvicente]

Hey waf, 

Thank you for letting me know. To help us improve, please share your feedback to implement better information regarding the compatibility.

Regards,

Daniel