How do I change the thermostat's temperature display from Fahrenheit to Celsius?
You can change the temperature scale in the Installer Setup (ISU) under Setup Number 125. Set the option to 0 for Fahrenheit or 1 for Celsius. Access the ISU by pressing and holding the Menu button for approximately 5 seconds from the Home Screen. (Page 7)
From the official Honeywell T3 Pro Programmable Thermostat manual, page 7
Have a follow-up question?
Answers from the official manual.
Common questions