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Nest Thermostat - Indicates heating, however heating system does not turn on

bkaufin52
Community Member

‎11-25-2024 03:29 PM

I have a Nest Thermostat (Information below) being used on a low pressure boiler system with a standing pilot control. The thermostat is configured for heat only with C-wire connected and verified 24VAC across the device for power. The thermostat randomly fails to initiate a heat command while the display states that the system is heating. I have verified that the control relay located in the boiler control unit does not energize under this condition. I have also verified that while the thermostat states it is heating, there is no 24VAC available at the W (Call for Heat)  terminal with reference to the common (C)

Once I shut the thermostat off, wait 10 seconds, then turn back to heat, the thermostat then calls for heat (verified 24VAC between W and C) and the heat call relay is then energized in the furnace control. This is how I have verified the issue is with the device, not the wiring, power, or furnace control. Is there an update that can resolve this issue (as it seems like a software failure within the device) or is it time to replace the device?

 

Heat Configuration = Propane (LP) - Radiators

Model - Thermostat-1.4

Software Version - 1.3-10

Battery State: OK

battery Voltage: 3.08 Volts

 

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2 REPLIES 2

ducs4rs
Community Member

‎11-26-2024 01:55 PM

did you happen to do a power test from the thermostat? 

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luciaaa
Community Specialist
Community Specialist

‎11-28-2024 04:46 PM - last edited on ‎12-03-2024 11:52 AM by Community Specialist

Hi, @bkaufin52,

 

Thank you so much for reaching out to the community. I’m truly sorry the heating system is not turning on. I know how important a reliable heating system is, especially during winter. I’m happy to help you! 

I really appreciate the detailed information you shared. To troubleshoot effectively, please provide the following information: 

  • Is the Nest thermostat newly installed?
  • When did the heating last work?
  • When was the last time you changed the furnace's air filter?
  • Have you experienced extremely cold weather lately?
  • Is it displaying any error code? 

Also, please confirm that the wires are securely attached to the terminals. Ensure at least ¼ to ½ inch of the copper wire is exposed, straightened, and fully inserted into each terminal. If necessary, strip and reinsert the wires.

Please let me know how it goes.

 

Best regards.

Ana

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