How do I enter the installer setup mode to configure the thermostat?
Press and hold both the up (s) and down (t) buttons simultaneously until the display changes. From there, press the t button to change settings, press s to advance to the next function, and press and hold both buttons together to exit and save all settings. (Page 6)
From the official Honeywell Pro Th3210d manual, page 6
Have a follow-up question?
Answers from the official manual.
Common questions