Nest smart thermostat low voltage

[hjf]

I have three Nest Learning thermostats that all work well for several years and all indicate 3.9V. I recently added a Nest Smart Thermostat to my fourth zone that doesn't need a smart thermostat. The problem is that this thermostat is indicating N260 error and only registers as receiving 2.8V which I know is not enough to keep the thermostat charged. Is there something different in the design of these thermostats that I will only be able to get the Learning thermostat to work properly in my two wire setup or is there an overall change in Nest designs that they all would not work in regular two wire setup  and need a C wire?

[maedacortez]

Hi hjf,

Thanks for reaching out! You're right, error code N260 indicates your thermostat isn't receiving enough power. Here are two ways to resolve this:

Install a C wire: This is the recommended solution as it provides a dedicated power source for your thermostat. You'll need to consult your thermostat's installation guide or a qualified electrician for proper installation.

Use the Nest Power Connector: This is an alternative solution that provides additional power without installing a C wire. You can find the Nest Power Connector here: Please visit Google store. 

I hope this helps! Let me know if you have any other questions.

Regards,

Manuel

[hjf]

Understood that the easy solution is install C wire or NPC but am curious whether it is a design difference and I would not have needed either if I had again used the smart learning model as I have three of those on the system working great without the C wire or NPC. I did install a NPC for the thermostat issue and the thermostat is working fine now.  

[maedacortez]

Hi hjf,

Thanks for your reply, The model that can work without  the Nest power connector or the C wire is the Nest Learning Thermostat but sometimes it will require the C wire when you HVAC system is not sending enough power. On the link you  can learn about the common or C wire. Besides here you go the link if you need to buy a new Nest Learning thermostat visit Google store.

Let me know if you have any questions.

Regards,

Manuel