About Your New Thermostat
All 8400 series thermostats
- Large, clear, backlit display is easy to read – even in the dark.
- Displays room temperature, temperature setting, and optional outdoor temperature.
- Front battery door access for fast, easy replacement.
- Built-in compressor protection.
- Circulation fan mode for air cleaning.
- Air filter, humidifier, dehumidifier, and HVAC service indicators.
- Auto backlight (activated with first button press).
Programmable models only (8463, 8465, 8466)
- Separately programmable weekday/weekend schedules.
- Easy-to-use temperature control can override the program schedule at any time.
- Progressive recovery
Model Number Location
To locate the model number, remove the battery cover.
Model 8444 Heat/Cool Non-Programmable
Model 8446 Heat Pump Non-Programmable
Model 8448 Heat/Cool or Heat Pump Multi-Stage Non-Programmable
Model 8463 Heat/Cool Programmable
Model 8465 Heat Pump Programmable
Model 8466 Heat/Cool or Heat Pump Multi-Stage Programmable
About your New thermostat – Non-Programmable Models
Controls & display overview – Models 8444, 8446, 8448
About Your New Thermostat – Programmable Models
Controls & display overview – Models 8463, 8465, 8466
Operation – ALL MODELS
Select system mode (OFF/HEAT/EM-HEAT/COOL/AUTO)
Press MODE to select:
AUTO: Thermostat automatically selects heating or
cooling depending on the indoor temperature.
OFF: Heating and cooling systems are off.
HEAT: Thermostat controls only the heating system.
COOL: Thermostat controls only the cooling system.
EM-HEAT: Thermostat controls emergency/auxiliary
heat. Heat pump will not operate. (Only for heat pumps
with auxiliary heat on models 8446, 8465, 8448HP and
8466HP.)
Change temperature setting
Applies to programmable versions (8463, 8465, 8466)
when in HOLD mode.
In AUTO use MODE to switch between the HEAT and COOL setting.
Operation – ALL MODELS
Select fan setting (ON/AUTO/CIRC)
Press FAN to select:
ON: Fan runs continuously. Use this mode for maximum air circulation/air cleaning.
AUTO: Fan runs only when the heating or cooling system is on.
CIRC: Same as AUTO, but if the fan has been off for 20
minutes the fan will be activated for a 10-minute cycle.
Use this mode for a balance of energy savings and air circulation/cleaning.
Reset Service Reminder Messages
Press and hold UP and DOWN together for three seconds to reset a service reminder message.
The thermostat can either be AC or battery-powered, or both. When wired to be AC powered, the batteries are optional and only provide backup power to the clock. The thermostat has a memory backup that saves the thermostat’s settings in case of a power interruption. The reset button located under the battery cover can be used to reset the thermostat back to factory defaults.
Operation & Programming – PROGRAMMABLE MODELS ONLY (8463, 8465, 8466)
- Press to enter time setting mode. Hour and AM/PM are flashing
- Press UP or DOWN to adjust the hour.
- Press MODE, the minutes flash. Press UP or DOWN to adjust the minutes.
- Press MODE, the day flashes. Press UP or DOWN to adjust day.
- Press MODW to end. “DONE” will display. The thermostat will return to normal mode if no key is pressed within 3 seconds.
Understanding program schedules
The daily schedule is split into four sections:
WAKE: 6am-8am – Temperature you would prefer to wake up to, until you leave for the day.
LEAVE: 8am-5pm – Temperature when you are away from the house during the day.
RETURN: 5pm-10pm – Temperature you would prefer to return to, until bedtime.
SLEEP: 10pm-6am – Temperature you would prefer during the night. The times shown are the defaults. The start time and temperature of each section can be changed to fit your schedule.
Operation & Programming – PROGRAMMABLE MODELS ONLY (8463, 8465, 8466)
Understanding program schedules
| Event | Event Designator | Start Time | Heat | Cool |
| 1 | Wake | 6:00AM | 70°F (21°C) | 78°F (26°C) |
| 2 | Leave | 8:00AM | 62°F (17°C) | 85°F (29°C) |
| 3 | Return | 5:00PM | 70°F (21°C) | 78°F (26°C) |
| 4 | Sleep | 10:00PM | 62°F (17°C) | 82°F (28°C) |
Progressive Recovery
The Progressive Recovery feature allows the thermostat to activate the heating and cooling equipment prior to an event in order to reach the desired temperature at the start of the next scheduled event.
Example: Set the Wake time to 6 am, and the temperature to 70°. The heat will come on before 6 am, so the temperature is 70° by the time you wake at 6.
Operation & Programming – PROGRAMMABLE MODELS ONLY (8463, 8465, 8466)
- Press PROG twice to enter program setting mode. Start time of the WAKE event is flashing.
- Press UP or DOWN to adjust the start time
- Press MODE, HEAT setting flashes. Press UP or DOWN to adjust the heat setting.
- Press MODE, COOL setting flashes. Press UP or DOWN to adjust the cool setting.
- Press MODE to advance the next event, and repeat
steps 2-5 for LEAVE, RETURN and SLEEP events. - Press MODE to change to weekend program. Repeat
steps 2-5 for the weekend program. - Press MODE to end. “DONE” will display.
The thermostat will return to normal mode if no key is
pressed in 3 seconds.
Operation & Programming – PROGRAMMABLE MODELS ONLY (8463, 8465, 8466)
Program schedule overrides (temporary, permanent)
Temporary program override
Press UP or DOWN to immediately adjust the temperature. This will temporarily override the temperature setting for the current programmed time period. The new temperature setting will be maintained until the next time period of the programmed schedule. To cancel the temporary override, adjust the temperature setting back to the programmed temperature, or press HOLD twice.
Permanent program override
Press HOLD to permanently hold the temperature at its current setting. This will override the temperature settings for all time periods of the programmed schedule. With the thermostat in permanent override, the thermostat temperature can be manually adjusted and will stay at that setting until the override is cancelled. To cancel the permanent override press HOLD.
ELECTRONIC THERMOSTAT FIVE YEAR LIMITED WARRANTY
Your Research Products Corporation Aprilaire® Thermostat unit is expressly warranted for five (5) years from date of installation to be free from defects in materials or workmanship. Research Products Corporation’s exclusive obligation under this warranty shall be to supply, without charge, a replacement for any thermostat which is found to be defective within such five (5) year period and which is returned, together with the date of installation, no later than thirty (30) days after said five (5) year period by you to either your original supplier or to Research Products Corporation, Madison, Wisconsin 53701. THIS WARRANTY SHALL NOT OBLIGATE RESEARCH PRODUCTS CORPORATION FOR ANY LABOR COSTS AND SHALL NOT APPLY TO DEFECTS IN WORKMANSHIP OR MATERIALS FURNISHED BY YOUR INSTALLER AS CONTRASTED TO DEFECTS IN THE THERMOSTAT ITSELF. IMPLIED WARRANTIES OF MERCHANTABILITY OF FITNESS FOR A PARTICULAR PURPOSE SHALL BE LIMITED IN DURATION TO THE AFORESAID FIVE YEAR PERIOD. RESEARCH PRODUCTS CORPORATION’S LIABILITY FOR INCIDENTAL OR CONSEQUENTIAL DAMAGES, OTHER THAN DAMAGES FOR PERSONAL INJURIES, RESULTING FROM ANY BREACH OF THE AFORESAID IMPLIED WARRANTIES OR THE ABOVE LIMITED WARRANTY IS EXPRESSLY EXCLUDED. THIS LIMITED WARRANTY IS VOID IF DEFECT(S) RESULT FROM FAILURE TO HAVE THIS THERMOSTAT INSTALLED BY A QUALIFIED HEATING AND AIR CONDITIONING CONTRACTOR. IF THE LIMITED WARRANTY IS VOID DUE TO FAILURE TO USE A QUALIFIED CONTRACTOR, ALL DISCLAIMERS OF IMPLIED WARRANTIES SHALL BE EFFECTIVE UPON INSTALLATION. Some states do not allow limitations on how long an implied warranty lasts or the exclusion or limitation of incidental or consequential damages, so the above exclusions or limitations may not apply to you. This warranty gives you specific legal rights and you may also have other rights which vary from state to state. This equipment if installed in strict accordance with the manufacturer’s instructions, complies with the limits for a Class B computing device pursuant to Subpart J of Part 15 of FCC Rules.
Warranty Registration
Please…Take a few minutes to visit us on-line at www.aprilaire.com to register your Aprilaire product.
If you do not have on-line access, please mail a postcard with your name, address, phone number, product purchased and date of purchase to: Research Products Corporation, P.O. BOX 1467, Madison, WI 53701