The Honeywell TH8320U1008 Manual you want for day-to-day use is the VisionPRO TH8000 Series Operating Manual, document number 69-1894EFS-03, a 96-page owner’s guide. It covers three models: the TH8110U (1 heat / 1 cool), the TH8320U (up to 3 heat / 2 cool), and the TH8321U (3 heat / 2 cool with dehumidification). This is a different document from the short Installation Guide (69-2693) that covers wiring and Installer Setup; the Operating Manual is about running the thermostat from the touch screen once it is already on the wall.
One navigation note, because it trips people up. On manual-download sites the page titled for the TH8320U1008 can serve the file labeled for the TH8110U. That is not a mistake in practice: all three models share this single 69-1894 Operating Manual, so the setup, schedule, and troubleshooting steps apply to the TH8320U as well. To confirm your exact model, the manual says to pull the thermostat from the wallplate and read the number printed on the back.
Here is what that guide gives you: the on-screen controls, how to set the clock, fan, and system mode, how to program the weekly schedule, how to hold or override it, how to replace the batteries, and what to check when something looks wrong.
Key Features of the TH8320U1008
The operating manual opens by listing what the thermostat does (page 2). The TH8320U is a backlit, touch-screen programmable thermostat with the following owner-facing capabilities:
- 7-day programmable schedules. You set four time periods each day, with different values for weekdays and weekends.
- Armchair programming. Schedules are edited with the thermostat pulled off the wallplate, so you work at a table rather than on a ladder.
- One-touch temperature override. Up/down arrows change the current setting at any time without reprogramming the schedule.
- Adaptive Intelligent Recovery. The thermostat starts heating or cooling early so the room reaches the programmed temperature at the scheduled time; the message “Recovery” appears while it is doing so.
- Compressor protection. The compressor is forced to wait a few minutes before restarting; the message “Wait” is shown during that delay.
- Automatic changeover. In Auto mode the thermostat chooses heating or cooling based on indoor temperature.
- Change-and-check reminders. Alerts tell you when to service or replace the furnace filter, humidifier pad, UV lamp, and batteries.
- Select-model extras. Some models display and control summer humidity, and accept an optional outdoor or indoor remote sensor. Dehumidification is tied to the TH8321U; treat those screens as model-specific on a TH8320U.
The main touch-screen controls are always along the bottom or sides (page 4). This lookup will help you orient on the display:
| Control | What it does |
|---|---|
| Up / down arrows | Adjust temperature setpoints and time values |
| SYSTEM | Select Heat, Cool, Off, Auto, or Em Heat |
| FAN | Select On, Auto, or Circ (circulation) |
| SCHED | Enter or edit the program schedule |
| HOLD | Hold a temperature (temporary, permanent, or vacation) |
| CLOCK | Set the displayed time |
| SCREEN | Lock the keypad for about 30 seconds to clean the display |
| MORE | Access extra screens such as humidity (select models) |
| MON-SUN day buttons | Choose which days a schedule edit applies to |
Document Structure
The 96-page guide is split into three blocks, so you can jump straight to what you need. Page numbers below match the printed manual’s table of contents.
About your new thermostat
- Thermostat features (p. 2)
- Programming at a glance (p. 3)
- Quick reference to controls (p. 4)
- Quick reference to status display (p. 5)
Programming and operation
- Clock setting (p. 6): the real-time clock stores date and time and updates for daylight savings on its own
- Fan setting (p. 7): On, Auto, or Circ (fan runs about 35% of the time)
- System setting (p. 8): Heat, Cool, Off, Auto, and Em Heat on heat pumps with auxiliary heat
- Using program schedules (p. 9-11): the four periods Wake, Leave, Return, Sleep, with recommended energy-saving values pre-set
- Program schedule overrides (p. 12-13): temporary and permanent “Hold”
- Vacation hold (p. 14): suspend the schedule for a set number of days, then resume automatically
- Special features (p. 15), Screen lock (p. 16), Screen cleaning (p. 17)
- Humidity display and control (p. 18-19, select models)
Appendices
- Battery replacement (p. 20)
- Advanced functions (p. 21-25): the installer-style settings reachable from the touch screen
- In case of difficulty (p. 26-27)
- Optional remote sensors (p. 28) and Limited warranty (p. 29)
The Advanced functions appendix is where the setup numbers live. You reach it by pressing SYSTEM, then pressing and holding the blank center key until the display changes. Each is a two-to-four-digit function you step through with the arrows. The owner-relevant ones include 0160 (program schedule on/off), 0320 (Fahrenheit or Celsius), 0330 (daylight savings), the reminder functions 0500 / 0510 / 0520, 0540 (two or four program periods), 0640 (clock format), and 0670 (screen lock).
How to Program the Schedule
The guide notes the thermostat ships pre-programmed, so most owners only adjust times and temperatures. To edit a schedule, follow the steps on page 11:
- Press SCHED, then press EDIT.
- Press the day buttons (MON through SUN) to pick which days you are changing; multiple days can be selected.
- Use the up/down arrows to set the start time for the Wake period.
- Set the Heat and Cool temperatures for that period.
- Move to LEAVE, RETURN, and SLEEP and repeat. Press CANCEL PERIOD to remove a period you do not want.
- Press DONE to save, or CANCEL to exit without saving.
To set a maintenance reminder aside after servicing equipment, press the RESET key to clear the alert (noted next to functions 0500, 0510, and 0520). For one-off comfort changes, use HOLD instead of reprogramming: a single arrow press is a temporary override until the next period, pressing HOLD applies a permanent hold until you cancel it, and pressing HOLD twice sets a vacation hold that resumes the schedule after a number of days you choose.
Important Safety Notices
This operating manual carries fewer hazards than the wiring guide, but the cautions it does print are worth following:
- Cooling below 50°F. The cover caution reads: “CAUTION: EQUIPMENT DAMAGE HAZARD. To prevent possible compressor damage, do not operate cooling system when outdoor temperature is below 50°F (10°C).”
- Protect the touch screen. “BE CAREFUL! Never use sharp instruments, such as a pencil or pen, to press touchscreen keys.” Use a fingertip, and press the SCREEN key to lock the display for cleaning.
- Battery handling. The manual states the thermostat contains a lithium battery that may contain perchlorate material and that special handling may apply, pointing to the California DTSC perchlorate guidance.
- Read and retain. The front matter instructs owners to “Read and save these instructions.”
Anything involving the low-voltage wiring, the circuit breaker, or opening the furnace is covered in the separate Installation Guide (69-2693), not this operating manual. For those tasks, shut off HVAC power before touching wires and call a licensed technician when in doubt. When a step is unclear or an error persists, refer to the “In case of difficulty” pages or contact Honeywell support rather than guessing.
Batteries and Basic Troubleshooting
Batteries are backup only if the unit was wired for AC power; the guide calls for three fresh AAA alkaline cells. Replace them when the “LO BATT” warning begins flashing, which appears about 30 days before the batteries are spent, or once a year and before any trip longer than a month. The “In case of difficulty” section (pages 26-27) maps the common symptoms:
- Display is blank. Check the circuit breaker, confirm the power switch at the heating and cooling equipment is on, verify the furnace door is fully closed, and confirm the AAA batteries are installed correctly.
- No response to key presses. Confirm the screen is not locked, and that setpoints sit inside the allowed ranges (heat 40-90°F, cool 50-99°F).
- Heat or cool will not come on. Set SYSTEM to Heat with the temperature above the room reading, or to Cool with it below. If “Wait” is on screen, the compressor protection timer is active; wait five minutes for a safe restart.
- Backlight looks dim. On battery power, check the cells; on AC power a low-level backlight that brightens on a keypress is normal.
Getting Help
The manual’s own contact block directs users to yourhome.honeywell.com or to Honeywell Customer Care at 1-800-468-1502. Before you call, note your model (from the label behind the wallplate), the exact message on the screen if one is showing, and whether the unit runs on AC power or batteries. If you need wiring or installer-setup details instead of operating steps, download the Installation Guide (69-2693) alongside this 69-1894EFS Operating Manual.
Download PDF: Honeywell Thermostat TH8320U1008 Operating Manual.pdf
