The serial number of an Alarm.com Smart Thermostat (ADC-T3000 or ADC-T2000) can be found on the box it came packaged in or locally on the thermostat. To find the serial number of an ADC-T3000: On the box: The serial number is the 16-digit located below the barcode on the sticker. On the thermostat: * Identiā¦