Aprilaire 8400 series Setup guide

8400 Series Thermostats
READ AND SAVE THESE INSTRUCTIONS
Safety &
Installation
Instructions

2 3
Installation location recommendations................................................................3
Outdoor temperature sensor (optional) ................................................................4
Thermostat mounting..............................................................................5
Power & reset options.............................................................................5
Wiring terminal ..................................................................................6
Wiring diagrams .................................................................................7
TABLE OF CONTENTS
INSTALLATION
SETUP & TESTING
REFERENCES
System setup instructions .........................................................................11
System test mode ...............................................................................16
Quick reference to controls & display
• Non-programmable models (8444, 8446, 8448).....................................................22
• Programmable models (8463, 8465, 8466).........................................................23
Thermostat features .............................................................................24
Troubleshooting .................................................................................25
Specifications...................................................................................27
INSTALLATION
INSTALLATION LOCATION RECOMMENDATIONS
Thermostat should be mounted:
• On an interior wall, in a frequently occupied space.
• Approximately 5‘ above floor.
• At least 18” from outside wall.
• Thermostat can be mounted to a vertical junction box.
Do not mount thermostat:
• Behind doors, in corners, or other dead air spaces.
• In direct sunlight, near lighting fixtures, or other
appliances that give off heat.
• On an outside or unconditioned area wall.
• In the flow of a supply register, in stairwells, or near
outside doors.
• On a wall with concealed pipes or ductwork.

4 5
OUTDOOR TEMPERATURE SENSOR (OPTIONAL)
Outdoor temperature can be measured by attaching an
8052 sensor to the S1 and S2 terminals. System setting
#05 (Remote sensor) is used to enable sensor.
Heat pump models can use the outdoor temperature to
effectively utilize the heat pump:
• When the outdoor temperature is less than the Low
Balance Point, the heat pump will be locked out and
only auxiliary heating will be used.
• When the outdoor temperature is higher than the High
Balance Point, the auxiliary heating will be locked out
and only the heat pump will be used to provide heating.
INSTALLATION
C
G
Y
W
RL
S1 S2 O/B W2 Y2
RC
• Install on side of building out of direct sunlight
(north side recommended).
• Mount above snow line.
• Mount at least 3’ away from exhaust vents and
condensing lines.
• Maximum wire length is 300’.
• Do not route wires along 120 VAC lines.
THERMOSTAT MOUNTING
1. Remove the back of the thermostat, by pressing the
tab on the bottom of the unit.
2. Pull wires through the opening on the back of the
thermostat.
3. Position and level the back of the thermostat on wall
and mark the hole locations with a pencil.
4. Drill 1/4” holes and insert supplied anchors (drywall only).
5. Place back over anchors, insert and tighten screws.
6. Seal wire entry holes to prevent drafts affecting
temperature readings.
INSTALLATION
POWER & RESET OPTIONS
The thermostat is dual power. It can either be AC or
battery powered, or both (to provide backup power for
the clock). Batteries are optional if the thermostat was
connected to AC power when installed.
For heat pump models (8446 and 8465) and universal
models (8448 and 8466) used in heat pump applications
24 VAC must be connected in order for the system fault
and emergency heat indicators to operate.
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.
The system settings will also be reset back to defaults.

6 7
WIRING TERMINAL
Wire specifications
18-24 gauge thermostat wire
Installation notes
• Ensure power at the HVAC equipment is off.
• Loosen screw terminals, insert stripped wire
and re-tighten.
• Push the excess wire back into the opening
and plug the wall opening to prevent drafts.
INSTALLATION
RC – 24 VAC supply cooling*
R– 24 VAC supply heating*
W– 1st stage heat / auxiliary
Y– 1st stage cooling / compressor
G– Fan
C– RC 24VAC common (optional when powered by batteries)
S1 & S2 – outdoor temperature sensor (optional)
O/B – Reversing valve
L– System fault indicator
W2 – 2nd stage heat / auxiliary
Y2 – 2nd stage cooling / compressor
*Jumper between RC & R is used in single transformer systems
(see wiring diagrams).
C
G
Y
W
RL
S1 S2 O/B W2 Y2
RC
WIRING – MODEL 8463 & 8444 SINGLE
TRANSFORMER (USE JUMPER WIRE)
INSTALLATION
C
G
Y
W
RS1 S2
RC
HEATING
COOLING
FAN
OUTDOOR TEMP
SENSOR
JUMPER
TRANSFORMER
WIRING – MODEL 8463 & 8444 TWO
TRANSFORMERS (REMOVE JUMPER WIRE)
C
G
Y
W
RS1 S2
RC
HEATING
COOLING
FAN
OUTDOOR TEMP
SENSOR
HEATING
TRANSFORMER
COOLING
TRANSFORMER

8 9
WIRING – MODEL 8465 & 8446 SINGLE
TRANSFORMER (USE JUMPER WIRE)
INSTALLATION
AUX HEATING
COMPRESSOR
FAN
REVERSE VALVE
FAULT DETECT
OUTDOOR TEMP
SENSOR
JUMPER
TRANSFORMER
C
G
Y
W
RL
S1 S2 O/B
RC
WIRING – MODEL 8465 & 8446 TWO
TRANSFORMERS (REMOVE JUMPER WIRE)
AUX HEATING
COMPRESSOR
FAN
REVERSE VALVE
FAULT DETECT
OUTDOOR TEMP
SENSOR
AUX HEATING
TRANSFORMER
HEAT PUMP
TRANSFORMER
C
G
Y
W
RL
S1 S2 O/B
RC
WIRING – MODEL 8466 & 8448 SINGLE
TRANSFORMER (USE JUMPER WIRE)
FOR HEAT/COOL SYSTEM
INSTALLATION
1st HEATING
1st COOLING
FAN
2nd HEATING
2nd COOLING
OUTDOOR TEMP
SENSOR
NOT USED NOT USED
JUMPER
TRANSFORMER
C
G
Y
W
RL
S1 S2 O/B W2 Y2
RC
WIRING – MODEL 8466 & 8448 TWO
TRANSFORMERS (REMOVE JUMPER WIRE)
FOR HEAT/COOL SYSTEM
1st HEATING
1st COOLING
FAN
2nd HEATING
2nd COOLING
OUTDOOR TEMP
SENSOR
NOT USED NOT USED
HEATING
TRANSFORMER
COOLING
TRANSFORMER
C
G
Y
W
RL
S1 S2 O/B W2 Y2
RC

10 11
INSTALLATION
WIRING – MODEL 8466 & 8448 SINGLE
TRANSFORMER (USE JUMPER WIRE)
FOR HEAT PUMP SYSTEM
1st AUX HEATING
1st COMPRESSOR
FAN
REVERSE VALVE
FAULT DETECT
2nd AUX HEATING
2nd COMPRESSOR
OUTDOOR TEMP
SENSOR
HEAT PUMP
TRANSFORMER
C
G
Y
W
RL
S1 S2 O/B W2 Y2
RC
JUMPER
1st AUX HEATING
1st COMPRESSOR
FAN
REVERSE VALVE
FAULT DETECT
2nd AUX HEATING
2nd COMPRESSOR
OUTDOOR TEMP
SENSOR
HEATING
TRANSFORMER
HEAT PUMP
TRANSFORMER
C
G
Y
W
RL
S1 S2 O/B W2 Y2
RC
WIRING – MODEL 8466 & 8448 TWO
TRANSFORMERS (REMOVE JUMPER WIRE)
FOR HEAT PUMP SYSTEM
SYSTEM SETUP INSTRUCTIONS
How to enter the system setup menu to change
system settings
Press repeatedly until system is set to OFF.
Press and hold and for three seconds.
The screen of the first setting will be displayed.
SETUP & TESTING
Press or to change the setting.
Press to change to the next option.
Press after the last setting. “DONE” will be
displayed.
The thermostat will save changes and return to Normal
mode if no key is pressed for 20 seconds.
To reset all system settings back to default, press the
RESET button located under the battery door.
The following instructions show how to enter the system setup menu and change settings. The table on the
following pages lists the settings and their details. Default settings are shown in bold. Some settings are only
available to certain models, and some are specific to thermostats set to heat pump mode.
SYSTEM SETTING NUMBER
SETTING VALUE

12 13
SETUP & TESTING
SYSTEM SETUP INSTRUCTIONS (CONTINUED)
Thermostat models 8448 & 8466 have the option of being used in heat pump or heat/cool systems. The equipment
type switch located on the back of the thermostat’s face is used to select this. System setting number 00 will only be
shown on these models to display the position of the equipment type switch.
EQUIPMENT
TYPE SWITCH
HEAT PUMP
HEAT/COOL
SETUP & TESTING
System setting Setting range, default in bold
00 Equipment type (8466, 8448)
(Set by the equipment type switch)
0 : heat/cool
1 : heat pump
01 Temperature scale 0 : Fahrenheit
1 : Celsius
02 Heat/Cool: Fan control in heating
Heat Pump: Auxiliary equipment type
0 : Gas or oil furnace (Equipment controls fan)
Note: Used for Dual Fuel applications
1 : Electric (Thermostat controls fan)
03 Offset temperature for internal sensor 0° : No offset applied
–4°F to +4°F (–2°C to +2°C)
04 Auto changeover mode 0 : Auto changeover mode is disabled
1 : Auto changeover mode is enabled
05 Outdoor temperature sensor 0 : No outdoor temperature sensor attached
1 : Outdoor temperature sensor attached
06 Compressor minimum off time 5 minutes
1 to 5 minutes in 1 minute steps
07 Heating minimum off time 2 minutes
1 to 5 minutes in 1 minute steps
08 Equipment minimum on time 2 minutes
1 to 5 minutes in 1 minute steps
SYSTEM SETUP INSTRUCTIONS (CONTINUED)

14 15
SETUP & TESTING
System setting Setting range, default in bold
09 1st stage differential 1°F (0.5°C)
1°F to 4°F (0.5°C to 2°C)
10 2nd stage differential (8448, 8466) 1°F (0.5°C)
1°F to 4°F (0.5°C to 2°C)
11 3rd and 4th stage differential (8448HP, 8466HP) 1°F (0.5°C)
1°F to 4°F (0.5°C to 2°C)
12 Reverse valve (8446, 8448HP, 8465, 8466HP) 0 – O/B energized in cooling (O)
1 – O/B energized in heating (B)
13 Stage rate* 2
1 to 5 or “OFF” to disable
14 Deadband (auto mode) 3°F (2°C)
2°F to 5°F (1°C to 3°C)
15 Progressive recovery (8463, 8465, 8466) 0 : Progressive recovery is disabled
1 : Progressive recovery is enabled
16 Low Balance Pt. (8446, 8448HP, 8465, 8466HP)
System setting 05 must be enabled
20°F (-7°C)
0°F to 60°F (-18°C to 16°C) or “OFF” to disable
*Accumulation of equipment run time in equipment staging determination.
1 = more rapid staging of equipment (comfort).
5 = slower staging of equipment (economy).
SYSTEM SETUP INSTRUCTIONS (CONTINUED)
SETUP & TESTING
System setting Setting range, default in bold
17 High Balance Pt. (8446, 8448HP, 8465, 8466HP)
System setting 05 must be enabled
65°F (18°C)
0°F to 80°F (-18°C to 27°C) or “OFF “ to disable
19 Program format (8463, 8465, 8466) 0 – 5/2 program (Weekdays and Weekends)
1 – 5/1/1 program (Weekdays, Sat. and Sun.)
20 Change air filter OFF
1, 3, 6, 12 months or “OFF” to disable
21 Change water panel**
Set number of months until reminder is required
OFF
1 to 12 months or “OFF” to disable
22 Humidifier type** 0 : Flow through type humidifier (1 reminder per season)
1 : Drain-less type humidifier (2 reminders per season)
23 Service dehumidifier OFF
1 to 12 months or “OFF” to disable
24 Service HVAC OFF
1 to 12 months or “OFF” to disable
25 2 or 4 Program Events 0 = WAKE and SLEEP
1 = WAKE, LEAVE, RETURN, SLEEP
**If humidifier type is set to Drain-less, then the first reminder is based on the system setting 21, second
reminder will activate 3 months later. If humidifier type is set to Flow through, then the first reminder is based
on system setting 21, second reminder will activate 12 months later.
SYSTEM SETUP INSTRUCTIONS (CONTINUED)

16 17
SYSTEM TEST MODE
The system test mode is used to test a system after installation. The outputs of the thermostat can be manually
activated one at a time to test their function. The following instructions show how to enter the test mode and turn
outputs on and off. The charts on the following pages show all of the options for each model.
The test steps are:
SETUP & TESTING
Test
Number
Heat/Cool Models
8444, 8463, 8448HC, 8466HC
Heat Pump Models
8446, 8465, 8448HP, 8466HP
50 Heating (W) (W2) Aux Heating (W) (W2)
51 Cooling (Y) (Y2) Compressor Cooling (Y) (Y2)
52 Fan (G) Compressor Heating (Y) (Y2)
53 Fan (G)
How to enter the system test menu
Press repeatedly until system is set to OFF.
Press and hold and for three seconds.
The screen of the first test step #50 is displayed:
SYSTEM TEST MODE (CONTINUED)
SETUP & TESTING
Press to turn on the output (01). For multi stage
output, press again to turn on the 2nd stage (02).
Press to turn off the output (00).
Press to change to the next test step.
Press after the last test step. “DONE” will be
displayed.
The thermostat will return to Normal mode if no key is
pressed in 20 seconds.
SYSTEM TEST
NUMBER
OUTPUT STATUS
FLASHES IF 24VAC
IS NOT PRESENT
MODE (SW1 SETTING
8448 & 8466 ONLY)

18 19
SETUP & TESTING
Test steps for 8444 & 8463
Step Key Input
System Setting Display (Output)
#2
01
HEATING
ON (W)
01
COOLING
ON (Y)
01
FAN ON
(G)
#50 Heat [UP] 0 : Gas ON
1 : Elec ON ON
[DOWN]
#51 Cool [UP] ON ON
[DOWN]
#52 Fan [UP] ON
[DOWN]
SETUP & TESTING
Test steps for 8448HC & 8466HC
Step Key Input
System Setting Display (Output)
#2
01
HEATING
ON (W)
02
HEATING
ON (W2)
01
COOLING
ON (Y)
02
COOLING
ON (Y2)
01
FAN ON
(G)
#50 Heat
1st [UP] 0 : Gas ON
1 : Elec ON ON
2nd [UP] 0 : Gas ON ON
1 : Elec ON ON ON
[DOWN]
#51 Cool
1st [UP] ON ON
2nd [UP] ON ON ON
[DOWN]
#52 Fan [UP] ON
[DOWN]

20 21
Test steps for 8446 & 8465
Step Key Input
System Setting Display (Output)
#2 #12
01 AUX
HEATING
ON (W)
01
COOL/HEAT
ON (Y)
01
FAN ON
(G)
O/B
#50 Aux [UP] 0 : Gas
ON
1 : Elec ON ON
[DOWN]
#51 Cool
[UP] 0 : O ON ON ON
1 : B ON ON
[DOWN] 0 : O ON
1 : B
#52 Heat
[UP] 0 : O ON ON
1 : B ON ON ON
[DOWN] 0 : O
1 : B ON
#53 Fan [UP] ON
[DOWN]
SETUP & TESTING
Test steps for 8448HP & 8466HP
Step Key Input
System Setting Display (Output)
#2 #12
01 AUX
HEATING
ON (W)
02 AUX
HEATING
ON (W2)
01
COOL/HEAT
ON (Y)
02
COOL/HEAT
ON (Y2)
01
FAN ON
(G)
O/B
#50 Aux
1st [UP] 0 : Gas ON
1 : Elec ON ON
2nd [UP] 0 : Gas ON ON
1 : Elec ON ON ON
[DOWN]
#51 Cool
1st [UP] 0 : O ON ON ON
1 : B ON ON
2nd [UP] 0 : O ON ON ON ON
1 : B ON ON ON
[DOWN] 0 : O ON
1 : B
#52 Heat
1st [UP] 0 : O ON ON
1 : B ON ON ON
2nd [UP] 0 : O ON ON ON
1 : B ON ON ON ON
[DOWN] 0 : O
1 : B ON
#53 Fan [UP] ON
[DOWN]
SETUP & TESTING

22 23
QUICK REFERENCE TO CONTROLS & DISPLAY
NON-PROGRAMMABLE MODELS (8444, 8446, 8448)
NOTE: BACKLIGHT IS ACTIVATED WITH FIRST BUTTON PRESS AND AUTOMATICALLY TURNS OFF.
CURRENT INDOOR TEMPERATURE
SYSTEM MODE
SETTING
FAN SETTING
SYSTEM MODE
FAN SETTING
BATTERY DOOR
MESSAGE CENTER LOW BATTERY WARNING
QUICK REFERENCE CARD
OUTDOOR TEMPERATURE (OPTIONAL)
TEMPERATURE SETTING
EQUIPMENT STATUS
EMERGENCY HEAT (RED)
SYSTEM FAULT (YELLOW)
INDICATOR SHOWS THROUGH HOUSING
HEAT PUMP MODELS ONLY
UP
DOWN
QUICK REFERENCE TO CONTROLS & DISPLAY
PROGRAMMABLE MODELS (8463, 8465, 8466)
NOTE: BACKLIGHT IS ACTIVATED WITH FIRST BUTTON PRESS AND AUTOMATICALLY TURNS OFF.
CURRENT INDOOR TEMPERATURE
SYSTEM MODE
SETTING
FAN SETTING
SYSTEM MODE
FAN SETTING
BATTERY DOOR
MESSAGE CENTER LOW BATTERY WARNING
QUICK REFERENCE CARD
OUTDOOR TEMPERATURE (OPTIONAL)
TEMPERATURE SETTING
EQUIPMENT STATUS
EMERGENCY HEAT (RED)
SYSTEM FAULT (YELLOW)
INDICATOR SHOWS THROUGH HOUSING
HEAT PUMP MODELS ONLY
UP
DOWN
PROGRAM
CURRENT
SCHEDULE
PERIOD
HOLD
CURRENT TIME

24 25
THERMOSTAT FEATURES
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.
• Dual power option (Battery or 24 VAC).
• Front battery door access for fast, easy replacement.
• Built in compressor protection.
• Circulation fan mode for air cleaning.
• Water panel, dehumidifier, air filter, and HVAC
service indicators.
• System test mode.
PROGRAMMABLE MODELS ONLY
(8463, 8465, 8466)
• Separately programmable weekday/weekend
schedules.
• Easy to use temperature control can override
program schedule at any time.
• Progressive recovery. 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.
TROUBLESHOOTING
DISPLAY IS BLANK
• Check circuit breaker and reset if necessary.
• Make sure power switch at heating & cooling
system is on.
• Make sure furnace door is closed securely.
• If thermostat is battery powered, make sure fresh AA
alkaline batteries are correctly installed.
TEMPERATURE SETTINGS DO NOT CHANGE
Make sure heating and cooling temperatures are set to
acceptable ranges:
• Heat: 45° to 90°F (7° to 32°C).
• Cool: 50° to 99°F (10° to 37°C).
HEATING SYSTEM DOES NOT RESPOND
(“HEATING” APPEARS ON SCREEN)
• Check for 24 VAC at the equipment on the secondary
side of the transformer between power and
common. If voltage is not present, check the heating
equipment to find the cause of the problem.
• Check for 24 VAC between the heat terminal (W)
and the transformer common. If 24 VAC is present,
the thermostat is functional. Check the heating
equipment to find the cause of the problem.
• Check for loose or broken wires between the
thermostat and the heating equipment.

26 27
TROUBLESHOOTING
COOLING SYSTEM DOES NOT RESPOND
(“COOLING” APPEARS ON SCREEN)
• Check for 24 VAC at the equipment on the secondary
side of the transformer between power and
common. If voltage is not present, check the cooling
equipment to find the cause of the problem.
• Check for 24 VAC between the cooling terminal (Y)
and the transformer common. If 24 VAC is present,
the thermostat is functional. Check the cooling
system to find the cause of the problem.
• Check for loose or broken wires between the
thermostat and the cooling equipment.
FAN DOES NOT TURN ON IN A CALL FOR HEAT
• Check System Setting #02 (Fan Control), to make
sure the fan control is properly set to match the type
of system (see page 11).
HEAT PUMP ISSUES COOL AIR IN HEAT MODE,
OR WARM AIR IN COOL MODE
• Check System Setting #12 (Reversing Valve), to make
sure it is properly configured for your system (see
page 11).
HEAT/COOL BOTH ON AT SAME TIME
• Check SW1 (Equipment Type), to make sure it is set
to match the installed heating/cooling equipment
(see page 12).
• Check to make sure heating and cooling wires are
not shorted together.
HEATING EQUIPMENT IS RUNNING IN
COOL MODE
• Check SW1 (Equipment Type), to make sure it is set
to match the installed heating/cooling equipment
(see page 12).
“HEATING” IS NOT DISPLAYED
• Change the System Mode to Heat, and set
the temperature level above the current room
temperature.
“COOLING” IS NOT DISPLAYED
• Change the System Mode to Cool, and set
the temperature level below the current room
temperature.
SPECIFICATIONS
Electrical
Operating voltage 24 VAC (18 – 30 VAC)
Current Maximum: 2.5A (total), 1.0A (single output)
Maximum surge current: 5A
Power supply
Dual power. Can be battery or 24 VAC powered.
When both the sources are available, battery will be used as
back up power.
Battery power Battery power: AA size alkaline battery x 2
Battery life: Approximately 1 year
Environment
Temperature Operating: 32° to 120°F (0° to 48.9°C)
Shipping: -30° to 140°F (-34.4° to 60°C)
Relative humidity Operating: 5% to 90% R.H. (non-condensing)

28
SPECIFICATIONS
Thermal
Outdoor temperature sensor Maximum distance: 300 feet
Room temperature measurement Display range: 32° to 99°F (0° to 40°C)
Outdoor temperature measurement Display range: -20° to 130°F (-30° to 55°C)
Temperature setting range Heat: 45° to 90°F (7° to 32°C)
Cool: 50° to 99°F (10° to 37°C)
P.O. Box 1467 • Madison, WI 53701-1467 • Phone: [phone] • Fax: [phone]
www.aprilairepartners.com
61000652 8.16
B2204777E © 2016 Aprilaire – A division of Research Products Corporation