The answer to 'when to service thermostat' is that you should service your thermostat at least once a year, or whenever you notice any issues with its performance. Proper thermostat maintenance helps ensure your HVAC system is running efficiently and keeps your home comfortable.
During an annual thermostat service, an HVAC technician will clean the device, check the batteries, and test the calibration to ensure it is accurately reading and regulating the temperature in your home. They may also check for any loose wiring connections or other potential problems that could impact the thermostat's function.