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Weil-Mclane boiler and Google Nest Learning Thermostat

NJMusicMan
Community Member

We have a 2019 Weil-McClane CGi Gold boiler that has always functioned well. We installed a Google Nest thermostat (two wires (red and white). This thermostat works fine, until it goes into Eco mode. Upon re-start it will send a signal to boiler to heat to say 66 degrees. However, it constantly cycles on and off, firing the igniter, turning on the exhaust, and running gas to the burner for a few seconds, but never staying lit. It does this over a period of several hours, before it eventually stays lit enough to heat the boiler and push hot water into our radiators. 

This only occurs at night. I called a plumber, who came during the day, and he found no issues. I receive no errors from the Nest, and only see extensive heating usage reflecting the constant attempts to stay lit at night. If I cannot figure this out, I will have to go back to analog. 

1 REPLY 1

zoeuvre
Community Specialist
Community Specialist

Hi NJMusicMan,

 

Uh-oh! Are you located in North America or Europe? Could you send us a wiring photo of your previous thermostat wire and a photo of how you connected the wires to the Nest Learning Thermostat? Alsom, kindly check on the following: 

 

  1. Double-check the wiring connections between the Nest Thermostat and the boiler. Ensure that the red wire is connected to the RC or RH terminal, and the white wire is connected to the W1 terminal on both the thermostat and the boiler. Make sure the connections are secure and properly seated.
  2. Confirm that the Nest Thermostat is receiving adequate power and voltage using a voltmeter or multimeter. Low voltage or intermittent power supply could result in issues with the thermostat's operation. Check the power source and the wiring to ensure they are functioning correctly.
    • Set the dial to 200 VAC.
      • If the multimeter doesn’t have a 200 setting, choose 100 or 250 VAC.
      • The general rule of thumb is don’t set it too high (500+) or too low (50).Place the red lead on the RC or RH wire.
    • Place the black lead on the other wire being tested (W1, Y1 or C).
    • The normal readout should be somewhere between 20 and 30 V (24 V is most common).
  3. Review the Eco mode settings on your Nest Thermostat. Make sure the temperature settings and the schedule are properly configured. Consider adjusting the Eco mode settings or disabling it temporarily to see if the issue persists.
  4. Ensure that your Nest Thermostat's firmware and software are up to date. Check for any available updates through the Nest app or the Nest website. Updated software can sometimes resolve compatibility issues or bugs.
  5. Try resetting the Nest Thermostat to its factory settings and reconfigure it from scratch by going to Settings > Reset > All Settings. This process can help resolve any software or configuration-related issues that may be causing the problem.

 

Let us know how it goes.

 

Best,

Zoe