How do I enter the Installer Setup to configure my thermostat system?
The thermostat enters installer setup automatically the first time it is powered up during installation. To re-enter the System Setup from the Home Screen later, press and hold the Menu button for approximately 5 seconds. Then select options and use Edit (-) to change values before pressing Next (+) to advance.
From the official Honeywell T3 Pro Programmable Thermostat manual, page 6
Have a follow-up question?
Answers from the official manual.
Common questions