A Smart Thermostat Keeps Changing the Temperature: Find the Setting That Owns the Setpoint

Record the target, actual temperature and time

When a smart thermostat changes the temperature by itself, first determine whether the requested target actually changed. A new target is different from a furnace failing to meet an unchanged request. Capture both numbers and the time before resetting the device.

A Reddit Nest owner discovered a lower target associated with Rush Hour Rewards and said they had forgotten enrolling. The same post also described a separate period when the room fell well below its displayed target. The enrollment explains a target adjustment; it does not by itself diagnose the separate furnace interruption.

Save the active mode, event notice, schedule and available history. Those records let support distinguish an automatic instruction from a loss of heating capability. If the target stayed fixed while the house became cold, pursue equipment diagnosis as well.

Source: Rush Hour Rewards or my furnace · Google: How Nest thermostats work with Rush Hour Rewards

Separate the rules that can request another temperature

A schedule, learning feature, hold expiration or authorized smart-home integration can change the ordinary target. Nest Eco behavior can also use different temperature limits when the home is considered away. Google documents differences by model, so inspect the current Eco or presence setting rather than assuming that turning off one schedule disables every automatic feature.

A hold may last until a chosen time, the next scheduled activity, or cancellation, depending on the model and settings. Write down its actual expiration. Avoid stacking several routines that change the same thermostat at nearly the same time; their names should identify their purpose.

Safety Temperatures are a separate protection. Google says these can activate heating or cooling even when ordinary thermostat operation is off. That is not the same as a learned comfort schedule, and disabling normal scheduling is not a reason to disable protective limits.

Source: Google: Eco Temperatures and Eco when away · ecobee: Get the most out of your thermostat · Google: Thermostat Safety Temperatures

An enrolled energy event is a separate control path

Google describes Rush Hour Rewards as an enrolled program that may adjust the target before or during an energy event. Confirm the current program terms, supported manual controls and event notice; owning a compatible thermostat alone does not establish enrollment.

California program names and providers change. PG&E’s current Automated Response Technology program enrolls customers through participating technology providers, and registered equipment can respond to grid events. Check the customer’s actual account and provider notices instead of assuming an old SmartAC description or another utility’s terms apply.

Illustrative scenario: the afternoon cooling target rises while a program event is shown. Record that notice and use the program’s supported override if the room is uncomfortable. Check the program terms for how an override affects event participation. Then check the stated end time and whether the normal schedule resumes. If no event is present, investigate the local schedule, Eco state or another authorized app rather than calling the event the cause.

Source: Google: How Nest thermostats work with Rush Hour Rewards · PG&E: Automated Response Technology

Test the next change without erasing the evidence

List the thermostat account, authorized household members, connected apps and enrolled program. Compare their timestamps with the unwanted change. Make one understood settings correction and watch the next real transition; a factory reset can remove useful history without identifying the source.

A useful handoff states who controls the ordinary schedule, how long a manual hold lasts, and where an energy-event notice appears. Test the supported manual override and the return to ordinary operation. Keep equipment service separate if actual temperature still fails to follow a stable target.

Source: Google: How Nest thermostats work with Rush Hour Rewards · Google: Eco Temperatures and Eco when away · ecobee: Get the most out of your thermostat

Put it into practice

A decision table to keep handy