Aprilaire 8476 User manual

Model 8476 Thermostat with
Event-Based™Air Cleaning
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 ..........................................................................9
System test mode ...............................................................................14
Quick reference to controls & display................................................................18
Thermostat features .............................................................................19
Troubleshooting .................................................................................20
Specifications...................................................................................22
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 applications 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 & 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.
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 – 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 – 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 – 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

8 9
INSTALLATION
WIRING – 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 – 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 return to Normal mode if no button
is pressed in 3 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 based on other setting values.
SYSTEM SETTING NUMBER
SETTING VALUE

10 11
SETUP & TESTING
SYSTEM SETUP INSTRUCTIONS (CONTINUED)
The Model 8476 thermostat has the option of being used in heat pump or heat/cool systems. Switch SW1 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 SW1.
SW1
HEAT PUMP
HEAT/COOL
SETUP & TESTING
System setting Setting range, default in bold
00 Equipment type (Set by SW1) 0 : heat/cool
1 : heat pump
01 Temperature scale 0 : Fahrenheit
1 : Celsius
02 Fan control in heating 0 : Gas or oil furnace (Equipment controls fan)
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 mode 0 : Auto mode is disabled
1 : Auto 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
08 Equipment minimum on time 2 minutes
1 to 5 minutes
SYSTEM SETUP INSTRUCTIONS (CONTINUED)

12 13
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 1°F (0.5°C)
1°F to 4°F (0.5°C to 2°C)
11 3rd stage differential (heat pump only) 1°F (0.5°C)
1°F to 4°F (0.5°C to 2°C)
12 Reverse valve (heat pump only) 0 – O/B energized in cooling (O)
1 – O/B energized in heating (B)
13 Integral factor period (P+I control)*
Set to OFF for proportional control only
4 minutes
1 to 5 minutes 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 0 : Progressive recovery is disabled
1 : Progressive recovery is enabled
* The integral factor is used in the equipment control algorithm to maintain the space temperature at set point.
A short integral factor period will increase the number of cycles per hour. (A short integral factor period will be more
comfortable.) A long integral factor period will lower the number of cycles per hour. (A long integral factor period will
be more economical.)
SYSTEM SETUP INSTRUCTIONS (CONTINUED)
SETUP & TESTING
System setting Setting range, default in bold
16 Low Balance Pt. (heat pump only)
System setting 05 must be enabled
20°F (–7°C)
1°F to 35°F (–17°C to 1°C) or “OFF” to disable
17 High Balance Pt. (heat pump only)
System setting 05 must be enabled
60°F (16°C)
40°F to 80°F (4°C to 27°C) or “OFF “ to disable
19 Program format 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)
** 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)

14 15
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 the output status for each test step for Heat/Cool and
Heat Pump mode.
The test steps are:
SETUP & TESTING
Test Number Heat/Cool Heat Pump
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 button is
pressed in 3 seconds.
SYSTEM TEST
NUMBER
OUTPUT STATUS
FLASHES IF 24VAC
IS NOT PRESENT
MODE (SW1 SETTING)

16 17
SETUP & TESTING
Test steps for Heat/Cool
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]
Test steps for Heat Pump
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

18 19
QUICK REFERENCE TO CONTROLS & DISPLAY
NOTE: BACKLIGHT IS ACTIVATED WITH FIRST BUTTON PRESS AND AUTOMATICALLY TURNS OFF.
Includes Event-Based™Air Cleaning
CURRENT INDOOR TEMPERATURE
SYSTEM MODE
SETTING
CLEAN AIR
SETTING
SYSTEM MODE
CLEAN AIR
BATTERY DOOR
CURRENT SCHEDULE PERIOD 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
UP
DOWN
PROGRAM
HOLD
CURRENT TIME
THERMOSTAT FEATURES
• Event-Based™ Air Cleaning.
• 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.
• Water panel and air filter service indicators.
• System test mode.
• 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.
HEAT PUMP ONLY