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Issues with Installing Two Nest Learning Thermostats in Commercial Building – Power & C Wire Problem

czubella
Community Member

‎10-24-2024 09:58 AM

We're installing two Nest Learning Thermostats to control two zones in a commercial building. Each thermostat is set up to manage a separate HVAC zone. The old thermostats worked fine, but after wiring the new Nest thermostats (as per the compatibility guidelines), both units are showing C wire/24V power issues.

Details:

  • The building has two HVAC zones.
  • We confirmed all wires are correctly connected at both thermostats and the control board (including the C wire).
  • The thermostats are not receiving continuous power, resulting in setup failures.
  • HVAC system is fully functional; everything worked fine with the previous thermostats.
  • This is a commercial property, and we’re wondering if the HVAC setup (possibly rooftop units) could be causing the issue.

Any insights on troubleshooting the C wire or setting up Nest thermostats for multi-zone control in a commercial building would be appreciated!

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1 REPLY 1

ByronP
Community Specialist
Community Specialist

‎10-31-2024 01:22 PM

Hi czubella,

 

Thank you for posting in the community. I'm sorry for the delayed response. I understand that you are experiencing issues with the Nest Learning Thermostat regarding power with the C wire/24V. I know how confusing this can be. I'm here to help.

 

Before I begin, please consider the following:

  • Your thermostat should automatically turn on once it’s connected to your system and your system is powered up.
  • During regular use, the screen may turn off if it doesn’t sense motion. It'll turn back on when it senses someone is nearby or when someone uses the app to control it.
  • Your Nest thermostat uses the voltage from your system’s wires to keep its internal battery charged. If the power to your system is switched off or there’s a blackout, the battery has enough capacity to keep working for a while. Your thermostat will also turn off features like Wi-Fi to preserve battery life before it must turn off completely. 
  • If there's a wiring report or other help message on your thermostat or in the app, follow the troubleshooting steps in Troubleshoot Nest thermostat help codes. 
  • Try manually restarting your thermostat.
  • If your Nest Learning Thermostat won't turn, please verify if there is blinking red or green light or no lights at all.

 

Please keep me posted. I'll look forward to your response.

 

Regards,

 

Byron

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