How do I access the installer setup (ISU) on my TH4210D, TH4110D, TH4110B thermostat?

Instructions:

1. To begin, press and hold the up and down buttons until the display changes.
2. Press down to change settings.
3. Press up to advance to next function.
4. Press and hold down and up to exit and save settings.

For more information on the ISU, please see pages 5 and 6 in the manual. Click here to download (English)