Nest Thermostat random calls for heat

[Ianscott]

I have two Nest Thermostats in the same house controlling two zones of radiators. Both are set the same, with a schedule in place, Time-to-temp ready, and with Auto Schedule off. This is not a new installation, it has worked well for a number of years..

One of the thermostats has started randomly calling for heat, at e.g. 3am, or at 2 pm, when the schedule is set at 17C and the zone actual temperature is typically 18C, the screen shows actual temperature of 18C with target temperature 20C! I would expect the call for heat to occur if the thermostat showed 16C with a target of 17C, but not a call to reach 20C when the schedule is set to 17C

Any thoughts please?

[luciaaa]

Hi, @Ianscott!

Thank you for posting in the community. I’m truly sorry the thermostat calls for heating suddenly. I understand that the importance of the proper functioning of your thermostat's schedule is important. Let’s work together and solve it!

I appreciate the detailed information you've shared, especially about the auto-schedule being off. To effectively troubleshoot, please provide the following information:

• What type of thermostat do you have?
• Is your HVAC system a conventional or a heat pump system? 
• Would you mind sharing a picture of your wiring configuration?
• When was the last maintenance check for your HVAC system?
• What other strange symptoms have you experienced since the problem started?
• Do you notice any intervals or specific patterns between these strange behaviors?
• Are there any error messages?
• What is your country of residence?

In the meantime, please try the following troubleshooting steps: 

• Set up a 24-hour schedule on your Nest thermostat. You can find instructions in this article: Nest thermostat temperature schedules and check the thermostat is following the newly created schedule.
• If the auto-schedule still doesn't work, try performing a factory reset and setting up the thermostat again.

For more information about time-to-temperature, please refer to this article: Learn about Nest thermostat displays.

Please let me know how it goes.

Best regards,

Ana