Wired 4th generation Nest just like the 1st generation removed. Doesn't work

[cmichaleross]

Wired 4th generation Nest just like the 1st generation removed. For geothermal water source heat pump system with 1 cooling stage and 2 heating stages.  Display on new thermostat (and on the Google Home app) shows all is fine and Stage 2 is heating - but the HP unit is not heating.  Wiring connections were and are: Y1, Y2, G, O, Rc, W2 Aux, C & *.

[Bent1]

Not sure what "Wired 4th generation Nest just like the 1st generation removed" means? I was was forced to upgrade Nest 1st Gen to 4th generation as the app was no longer working. The 4th generation Nest came with no installation/replacement instructions. Can I just plug the new thermostat into the old plate without changing the wiring?

[kcruzgonzalez]

Hello @cmichaleross,

Thank you for posting in the community. I understand you have replaced a 1st-generation Nest Thermostat with a 4th-generation Nest Learning Thermostat to control your geothermal water source heat pump system, and that while the thermostat display and the Google Home app indicate that Stage 2 Heating is active, the heat pump unit is not actually running or heating. Let's work together for a solution.

To proceed with advanced troubleshooting, I need to gather some specific details about your heat pump system and installation, as required for complex multi-stage setups.

Please provide the answers to the following questions. These details are essential for diagnosing why your heat pump is not responding to the heating call:

• Did the heating ever work with the new Nest thermostat? If not, did the heating work with the previous 1st Generation thermostat just before you removed it?
• What type of furnace/backup heat system do you have? (e.g., Is the auxiliary heat electric, gas, or another source?)
• Did you turn the HVAC system off or turn off any breakers near the heater/air handler during the installation process?

To ensure we do not lose track of any specialized settings for your geothermal unit, I need to confirm the wiring visually. Please provide a photo of your wire connections at the thermostat's base and/or the control board of your heat pump system.

• Please take a picture of your current and previous wire setup showing the wire colors and the terminal labels on the Nest backplate.

By getting this precise information, we can cross-check your geothermal system's specific requirements against the Nest's internal configuration and move toward a reliable fix.

Regards,

Kevin

[cmichaleross]

• Did the heating ever work with the new Nest thermostat? NO. If not, did the heating work with the previous 1st Generation thermostat just before you removed it? YES
• What type of furnace/backup heat system do you have? (e.g., Is the auxiliary heat electric, gas, or another source?)
• Did you turn the HVAC system off or turned off breakers near the heater/air handler during the installation process? YES
• previous wire setup showing the wire colors and the terminal labels on the Nest backplate - I tried to upload a picture but received a message that I do not have permission. Wiring connections are Y1, Y2, G, O, Rc, W2-Aux, C, *
•  

[kcruzgonzalez]

Hello @cmichaleross,

Thank you for providing the answers to my probing questions and confirming your wiring connections again. This is very helpful.

I apologize that you received an error message preventing you from uploading the picture of the wiring. Since the forum restricts direct image uploads, we can use a secure method to share the photo, which is crucial for systems like your geothermal heat pump.

Please use this alternative method to securely share the photo of your wiring:

1. Create a Folder: On your computer or mobile device, go to drive.google.com and create a new folder. Name it something simple like "Nest Wiring."
2. Add Your File: Upload the photo of the wires connected to the Nest back-plate into this new folder.
3. Get a Shareable Link:

• Right-click on the folder.
• Click Share.
• Under "General access," change the setting from "Restricted" to "Anyone with the link."
• Make sure the access level is set to "Viewer."
• Click Copy link.
• Paste the Link: Please paste the link into your next reply.

Also please take a screenshot of the digital wiring diagram shown in the Google Home app and share it with me using the secure link method outlined previously (Google Drive).

Here are the instructions to access the correct screen:

1. Open the Google Home app on your phone.
2. Tap on your Nest Thermostat icon.
3. Tap Settings (gear icon) in the top-right corner.
4. Tap Thermostat —— Wiring.
5. Take a screenshot of this page. The page should show a diagram of which terminals the Nest believes have wires (Y1, Y2, O, W2, C, etc.).

Thank you for your patience while we work through this specific geothermal setup. I look forward to seeing the screenshot so we can pinpoint the issue.

Regards,

Kevin