How do I access the installer setup (ISU) on the RTH111 thermostat?
Enter System Setup:
To enter system setup, press and hold both the up and down buttons until the display changes (approximately 5 seconds).
Press the up or down button to change the setting.
Press the up and down buttons simultaneously for one second to advance to the next function.
Press the RUN button to exit and save settings. Please note ISU changes when saved are permanently held in memory and will not be forgotten. If the thermostat is reverting to default programming troubleshoot the application.