Installation wiring connection

[Joseph1803]

Hello:

My original thermostats are :   Pro1 Iaq T701 for the upper and lower level. I successfully installed the Nest Thermostat on the main floor.  It works perfectly.  It has the : W,B,O,R,G cables connected. The HVAC system is gas, forced air. I’ve installed a C adapter at the control board for these set up.

The control board it’s a EWC-ST-2e and I would like to install a second google nest thermostat at the lower level which only have the R and W cables connected. I have an extra google C-adapter if needed.

Hoping you can help.

[Jeremyg]

Hi @Joseph1803!

Thanks for reaching out to the community. I am sorry that you are having issues with the installation of the wires on your thermostat, but no need to worry; help is here.

We appreciate all of your previous troubleshooting efforts to connect with our community. I am aware that you do have a c wire adapter attached to the control board. I need to know a few things about your thermostat in order to provide you with a better resolution

• What Nest thermostat model do you have? For your reference, you can check out this article on How to Tell Which Nest Thermostat You Have.
• Does the thermostat display show any error codes or messages?
• When was the thermostat installed?
• "What is the make and model of your HVAC equipment?
• What is the voltage in the red wire on your second thermostat? 

Keep me in the loop, and I can assist you with next steps.

Regards,

Jeremy.

[Joseph1803]

Thank you for your response and willingness to assist!

• Nest Thermostat Model: based on the site “ How to Tell Which Nest Thermostat You Have.“ I have the “Nest Thermostat” not the E or any version of the learning.

• Error Codes or Messages: The second thermostat shows the error E298.

• Installation Date: Both thermostats were installed on November 22, 2024.

• HVAC Equipment:  it’s a tempstar model: T9MPD100J14C1

• Voltage on the Red Wire it’s 0.

My assumption is that the transformer installed it’s only 24v for the control board and the two nest thermostat which might not be enough power for both thermostat but for one and in this case, for the main one.

Thank your for the help!

[Jeremyg]

Hi @Joseph1803!

Thanks for the update and letting us know that information that is going to help me to better assist you.

You have previously verified that the red wire is voltage-free, indicating that your HVAC system is not receiving any power. Therefore, the best course of action at this point is to have a technician inspect your HVAC system and red wire using the link below. Get installation help or HVAC service from a professional.

Best regards, 
Jeremy.