Advanced Thermostat Operations
48 ENV-VST-C - Operation / Reference Guide
Setting First and Second Stage Differentials
Differentials set the tightness of the temperature control to eliminate large temperature swings and prevent the HVAC
system from operating too often. Normally the second stage of heat is for auxiliary or emergency heat.
Perform these steps to set the first and second stage differentials:
1. From the Main screen, press Mode/Select to access the Thermostat Mode screen.
2. Use the navigation buttons to select Settings, and press Mode/Select. The Settings screen appears.
3. Use the navigation buttons to select Advanced Settings. Press Mode/Select to access the Security Code screen.
4. Enter the security code, and select Enter to access the User Preferences screen. See the Entering the Security Code
on page30 for more information.
5. Use the navigation buttons to highlight More, and press Mode/Select to access the second User Preferences screen.
6. On the second User Preferences screen, use the navigation buttons to highlight More, and press Mode/Select to
access the third User Preferences screen.
7. Use the navigation buttons to highlight Advanced Setup, and press Mode/Select to access the Advanced Setup
screen.
8. Use the navigation buttons to highlight More, and press Mode/Select to access the second Advanced Setup screen.
9. Use the navigation buttons to highlight Thermostat Setup, and press Mode/Select to access the Thermostat Setup
screen (FIG.49).
10. With First Stage Diff highlighted, press Mode/Select to activate it.
11. Press Mode/Select to indicate the first stage differential.
12. Use the navigation buttons to highlight Second Stage Diff, and press Mode/Select.
13. Press Mode/Select to indicate the second stage differential.
Setting the Deadband Temperature Difference
The Deadband is the temperature difference between the heating and cooling setpoints. The Deadband configuration
enforces a minimum separation between the two setpoints which determine when auto changeover between HVAC
heating and cooling mode will occur.
Perform these steps to set the deadband temperature difference:
1. From the Main screen, press Mode/Select to access the Thermostat Mode screen.
2. Use the navigation buttons to select Settings, and press Mode/Select. The Settings screen appears.
3. Use the navigation buttons to select Advanced Settings. Press Mode/Select to access the Security Code screen.
4. Enter the security code, and select Enter to access the User Preferences screen. See the Entering the Security Code
on page30 for more information.
5. Use the navigation buttons to highlight More, and press Mode/Select to access the second User Preferences screen.
6. On the second User Preferences screen, use the navigation buttons to highlight More, and press Mode/Select to
access the third User Preferences screen.
FIG. 49 Thermostat Setup screen (1 of 2)