I’ve had the same issue the heat turns on at the furnace but the thermostat is not asking for heat and it’s not indicating it’s on but the furnace is on and the heat went up to 76F and it was set to 65F. I had to shut the manual power switch off. Luckily this happened while I was home. And this has happened before - this was the 2nd time in 3 months maybe
My Nest is up to date
I'm sorry for the delay, and I know it has been a while, but I wanted to ensure that everything was covered here.
If you have the Nest Learning Thermostats or the Nest Thermostat E, please make sure to disable the auto-schedule. This usually causes a random or unexpected temperature change. Also, clearing all the scheduled temperatures would help.
Please let me know if that helps or if the issue still persists.
@Simontheplumber, just one quick final check in here since activity has slowed down. We'll be locking the thread in the next 24 hours, but if you still need help, we would be happy to keep it open. If there's more we can do, just let us know.
I appreciate the help, Jake and Mark.