Spec Sheet
Table Of Contents
- Application
- Features
- Contents
- Specifications
- System Installation
- Installation Options
- Guidelines for Installing RedLINK Devices
- Installing Equipment Interface Module (if used)
- Wiring 24 Vac Common
- Selecting Discharge and Return Air Temperature Sensor Mounting Locations
- Selecting Return Air Temperature Sensor Mounting Location
- Installing Discharge and Return Air Temperature Sensors
- Selecting Thermostat Location
- Installing Wallplate
- Power Optional REDLINK™ Accessories
- Performing Initial Setup
- Linking Thermostat to Equipment Interface Module (if used)
- Linking RedLINK™ Accessories
- Completing Initial Setup
- Adding RedLINK Accessories to the Thermostat
- Locating the Connect Buttons on RedLINK Accessories
- Finding Your Password (Date Code) to Access Installer Options
- Installer Options
- Making Changes to Installer Setup
- Installer Tests
- Operation
- Setting the time/date
- Setting the fan
- Setting system mode
- Preset Energy-Saving Schedules
- Adjusting program schedules
- Overriding schedules: residential use
- Overriding schedules: commercial use
- Viewing equipment status
- Setting vacation hold: residential use
- Setting holiday/event schedules: commercial use
- Setting custom events: commercial use
- Setting holiday schedule: commercial use
- Setting holiday override: commercial use
- Initiating occupancy mode: commercial use
- Remote setback: commercial use
- Adjusting humidification settings
- Adjusting dehumidification settings: residential use
- Adjusting dehumidification settings: commercial use
- Adjusting ventilation settings
- Customizing screen color
- Setting preferences
- Cleaning the thermostat screen
- Adjusting security settings
- Viewing dealer information
- Advanced Features
- Installer options
- Using the temperature display
- Using the humidity display
- Universal Outputs (U1, U2, U3)
- Universal Inputs (S1, S2, S3, S4)
- Alerts and Diagnostics
- Heat Pump and Backup Heat Operation
- Indoor Air Quality (IAQ) Control
- IAQ Reminders
- Customizable Reminders
- USB Port
- Commercial Features
- Overriding schedules: commercial use
- Setting holiday/event schedules: commercial use
- Setting custom events: commercial use
- Setting holiday schedule: commercial use
- Setting holiday override: commercial use
- Initiating occupancy mode: commercial use
- Ramp Rates
- Custom Names
- Remote Setback
- Economizer and Time of Day (TOD) Operation
- Pre-Occupancy Purge
- Battery Replacement
- Optional Accessories
- Portable Comfort Control
- Remote Indoor Sensors
- Backup Control
- Replacing a Thermostat
- Replacing an Equipment Interface Module
- Wiring
- EIM Wiring Diagrams
- THX9321 Thermostat Wiring Diagrams
- THX9321 Thermostat Wiring Diagrams Using Universal Relays to Control Heating or Cooling
- Wiring IAQ Equipment or a Heat/Cool Stage to the Universal Terminals
- Economizer Module Wiring Diagrams
- Wiring C7089U1006 Outdoor Sensor
- Wiring guide — Wired Indoor Sensors
- Zoning
- Troubleshooting
- Regulatory Information
THX9321 PRESTIGE
®
2.0 AND THX9421 PRESTIGE
®
IAQ WITH EIM
68-0311—07 100
HEAT PUMP AND BACKUP HEAT OPERATION
Heat pump with outdoor temperature lockouts
Outdoor temperature lockouts are optional. See Installer Setup options (ISU 3120).
Geothermal Radiant Heat
The thermostat can be setup to control Geothermal
Radiant Heat, Geothermal Forced Air Heat and Backup
Heat, all from one thermostat. The thermostat stages the
equipment starting with the Geothermal Radiant Heat
followed by Geothermal Forced Air Heat and then Backup
Heat as needed to maintain the desired temperature. The
thermostat allows you to set differential temperature
settings between each stage if you want the equipment to
stage a certain way (see ISU 3030 to ISU 3090, page 31).
For additional wiring diagrams, see page 144.
NOTE: To turn off Radiant Heat during the shoulder sea-
sons, install an outdoor reset control and connect
to the Radiant Heat or switch the thermostat to
Emergency Heat mode.
Electric Backup Heat (Backup Heat
Allowed to Run with Heat Pump)
HEAT MODE
The thermostat turns on Backup Heat only when the
indoor temperature drops to the selected Backup Heat
Differential setting or the Backup Heat Upstage Timer
Table 8. Heat Pump and Backup Heat Operation.
Backup Heat Type Backup Heat Operation Backup Heat Fan Operation
Electric forced air Allowed to run with heat pump Thermostat controls fan
Gas or oil forced air NOT allowed to run with heat pump Equipment controls fan
Hot water radiant heat Allowed to run with heat pump [n/a]
Hot water fan coil Selectable in installer setup Thermostat controls fan
Other Selectable in installer setup Selectable in installer setup
Heat pump only
Heat pump with backup heat as needed *
Backup heat only
Heat pump only
Heat pump or backup heat operates *
Backup heat only
Outdoor temperatureOutdoor temperature
Backup heat lockout
Backup heat lockout
Compressor lockout
Compressor lockout
* No backup heat unless indoor temperature drops to selected Backup Heat Differential setting, or Backup Heat
Upstage Timer expires. Heat pump stays ON when backup heat turns on.
* No backup heat unless indoor temperature drops to selected Backup Heat Differential setting, or Backup
Heat Upstage Timer expires. Heat pump turns OFF when backup heat turns on.
Backup heat allowed to run with heat pump (see table below)
Backup heat NOT allowed to run with heat pump (see tab
le below)