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Model 8476 Thermostat with  
Event-Based Air Cleaning  
Safety &  
Installation  
Instructions  
READ AND SAVE THESE INSTRUCTIONS  
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TABꢀE Of CONTENTS  
INSTAꢀꢀATION  
INSTAꢀꢀATION  
INSTAꢀꢀATION ꢀOCATION RECOMMENDATIONS  
Thermostat should be mounted:  
Installation location recommendations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  
Outdoor temperature sensor (optional) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  
Thermostat mounting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  
Power & reset options . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  
Wiring terminal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  
Wiring diagrams . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  
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Do not mount thermostat:  
On an interior wall, in a frequently occupied space.  
Approximately 5‘ above floor.  
• Behind doors, in corners, or other dead air spaces.  
• In direct sunlight, near lighting fixtures, or other  
appliances that give off heat.  
At least 18” from outside wall.  
On an outside or unconditioned area wall.  
Thermostat can be mounted to a vertical junction box.  
In the flow of a supply register, in stairwells, or near  
outside doors  
SETUp & TESTINꢁ  
On a wall with concealed pipes or ductwork.  
System setup instructions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  
9
System test mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  
14  
REfERENCES  
Quick reference to controls & display . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  
18  
Thermostat features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19  
Troubleshooting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  
Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  
20  
22  
2
3
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INSTAꢀꢀATION  
INSTAꢀꢀATION  
OUTDOOR TEMpERATURE SENSOR (OpTIONAꢀ)  
THERMOSTAT MOUNTINꢁ  
pOꢂER & RESET OpTIONS  
Outdoor temperature can be measured by attaching an  
• Install on side of building out of direct sunlight  
(north side recommended)  
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.  
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#
052 sensor to the S1 and S2 terminals System setting  
05 (Remote sensor) is used to enable sensor  
Mount above snow line.  
Heat pump applications can use the outdoor temperature  
to effectively utilize the heat pump:  
Mount at least 3’ away from exhaust vents and  
24 VAC must be connected in order for the system fault  
and emergency heat indicators to operate  
condensing lines  
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.  
Maximum wire length is 300’.  
The thermostat has a memory backup that saves the  
thermostat’s settings in case of a power interruption.  
Do not route wires along 120 VAC lines.  
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.  
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  
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2
3
. Remove the back of the thermostat, by pressing the  
tab on the bottom of the unit  
Pull wires through the opening on the back of the  
thermostat  
. Position and level the back of the thermostat on wall  
and mark the hole locations with a pencil  
4
5
6
. Drill 1/4” holes & insert supplied anchors (drywall only).  
. Place back over anchors, insert and tighten screws.  
RC  
R
W
Y
G
C S1 S2 O/B  
L W2 Y2  
. Seal wire entry holes to prevent drafts affecting  
temperature readings  
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5
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INSTAꢀꢀATION  
INSTAꢀꢀATION  
IRINꢁ TERMINAꢀ  
ire sꢃeciꢄications  
8-24 gauge thermostat wire  
ꢂIRINꢁ – SINꢁꢀE TRANSfORMER (USE  
JUMpER ꢂIRE) fOR HEAT/COOꢀ SYSTEM  
ꢂIRINꢁ – TꢂO TRANSfORMERS (REMOVE  
JUMpER ꢂIRE) fOR HEAT/COOꢀ SYSTEM  
RC – 24 VAC supply cooling*  
R – 24 VAC supply heating*  
1
– 1st stage heat / auxiliary  
Y – 1st stage cooling / compressor  
– Fan  
C – Common (optional when powered by batteries)  
S1 & S2 – outdoor temperature sensor (optional)  
O/B – Reversing valve  
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.  
– System fault indicator  
2 – 2nd stage heat / auxiliary  
Y2 – 2nd stage cooling / compressor  
*
Jumper between RC & R is used in single transformer systems  
(
see wiring diagrams).  
RC  
R
W
Y
G
C S1 S2 O/B L W2 Y2  
RC  
R
W
Y
G
C
S1 S2 O/B  
L
W2 Y2  
RC  
R
W
Y
G
C S1 S2 O/B  
L W2 Y2  
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INSTAꢀꢀATION  
SETUp & TESTINꢁ  
IRINꢁ – SINꢁꢀE TRANSfORMER (USE  
ꢂIRINꢁ – TꢂO TRANSfORMERS (REMOVE  
JUMpER ꢂIRE) fOR HEAT pUMp SYSTEM  
SYSTEM SETUp INSTRUCTIONS  
JUMpER ꢂIRE) fOR HEAT pUMp SYSTEM  
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.  
How to enter the system setuꢃ menu to change  
system settings  
press  
press  
or  
to change the setting  
to change to the next option.  
press  
repeatedly until system is set to OFF  
press  
displayed  
after the last setting. “DONE” will be  
press and hold  
and  
for three seconds  
The screen of the first setting 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  
SETTING VALUE  
SYSTEM SETTING NUMBER  
RC  
R
W
Y
G
C
S1 S2 O/B  
L
W2 Y2  
RC  
R
W
Y
G
C S1 S2 O/B  
L W2 Y2  
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SETUp & TESTINꢁ  
SETUp & TESTINꢁ  
SYSTEM SETUp INSTRUCTIONS (CONTINUED)  
SYSTEM SETUp INSTRUCTIONS (CONTINUED)  
System setting  
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  
Setting range, deꢄault in bold  
0 : heat/cool  
0
0
0
0 Equipment type (Set by Sꢂ1)  
1
: heat pump  
0
1
: fahrenheit  
: Celsius  
1 Temperature scale  
0
1
: ꢁas or oil ꢄurnace (Equiꢃment controls ꢄan)  
: Electric (Thermostat controls fan)  
2 Fan control in heating  
0
° : No oꢄꢄset aꢃꢃlied  
4°F to +4°F (–2°C to +2°C)  
Sꢂ1  
HEAT PUMP  
HEAT/COOL  
03 Offset temperature for internal sensor  
0 : Auto mode is disabled  
1
0
0
0
0
0
4 Auto mode  
: Auto mode is enabled  
0
1
: No outdoor temꢃerature sensor attached  
: Outdoor temperature sensor attached  
5 Outdoor temperature sensor  
6 Compressor minimum off time  
7 Heating minimum off time  
8 Equipment minimum on time  
5
1
minutes  
to 5 minutes in 1 minute steps  
2
1
minutes  
to 5 minutes  
2
1
minutes  
to 5 minutes  
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SETUp & TESTINꢁ  
SETUp & TESTINꢁ  
SYSTEM SETUp INSTRUCTIONS (CONTINUED)  
System setting  
SYSTEM SETUp INSTRUCTIONS (CONTINUED)  
Setting range, deꢄault in bold  
System setting  
Setting range, deꢄault in bold  
1
1
°f (0.5°C)  
°F to 4°F (0.5°C to 2°C)  
16 Low Balance Pt. (heat pump only)  
20°f (–7°C)  
1°F to 35°F (–17°C to 1°C) or “OFF” to disable  
0
1
1
9 1st stage differential  
System setting 05 must be enabled  
1
1
°f (0.5°C)  
°F to 4°F (0.5°C to 2°C)  
17 High Balance Pt. (heat pump only)  
60°f (16°C)  
40°F to 80°F (4°C to 27°C) or “OFF “ to disable  
0 2nd stage differential  
System setting 05 must be enabled  
1
1
°f (0.5°C)  
°F to 4°F (0.5°C to 2°C)  
0 – 5/2 ꢃrogram (ꢂeekdays and ꢂeekends)  
1 – 5/1/1 program (Weekdays, Sat. and Sun.)  
1 3rd stage differential (heat pump only)  
2 Reverse valve (heat pump only)  
19 Program format  
20 Change air filter  
0
1
– O/B energized in cooling (O)  
– O/B energized in heating (B)  
Off  
1
1
1, 3, 6, 12 months or “OFF” to disable  
3 Integral factor period (P+I control)*  
4 minutes  
21 Change water panel**  
Off  
Set to OFF for proportional control only  
1 to 5 minutes or “OFF” to disable  
Set number of months until reminder is required  
1 to 12 months or “OFF” to disable  
3
2
°f (2°C)  
°F to 5°F (1°C to 3°C)  
0 : flow through tyꢃe humidiꢄier (1 reminder ꢃer season)  
1 : Drain-less type humidifier (2 reminders per season)  
1
1
4 Deadband (auto mode)  
5 Progressive recovery  
22 Humidifier type**  
0
1
: Progressive recovery is disabled  
: progressive recovery is enabled  
**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.  
*
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 )  
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2
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SETUp & TESTINꢁ  
SETUp & TESTINꢁ  
SYSTEM TEST MODE  
SYSTEM TEST MODE (CONTINUED)  
How to enter the system test menu  
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  
press  
output, ꢃress  
to turn on the output (01) For multi stage  
again to turn on the 2nd stage (02)  
press  
repeatedly until system is set to OFF  
press and hold  
and  
for three seconds  
press  
press  
to turn off the output (00)  
The screen of the first test step #50 is displayed:  
to change to the next test step.  
after the last test step. “DONE” will be  
press  
The test steꢃs are:  
displayed  
Test Number  
Heat/Cool  
Heating (W) (W2)  
Cooling (Y) (Y2)  
Fan (G)  
Heat pumꢃ  
Aux Heating (W) (W2)  
Compressor Cooling (Y) (Y2)  
Compressor Heating (Y) (Y2)  
Fan (G)  
The thermostat will return to Normal mode if no button is  
pressed in 3 seconds  
5
5
5
5
0
1
2
3
FLASHES IF 24VAC  
SYSTEM TEST  
IS NOT PRESENT  
NUMBER  
MODE (SW1 SETTING)  
OUTPUT STATUS  
1
4
15  
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SETUp & TESTINꢁ  
SETUp & TESTINꢁ  
Test steꢃs ꢄor Heat/Cool  
Test steꢃs ꢄor Heat pumꢃ  
System Setting  
Disꢃlay (Outꢃut)  
01  
System Setting  
Disꢃlay (Outꢃut)  
01  
0
1
02  
02  
01  
fAN ON  
(ꢁ)  
01 AUX  
HEATINꢁ  
ON (ꢂ)  
ON  
ON  
ON  
ON  
02 AUX  
02  
01  
Steꢃ  
Key Inꢃut  
Steꢃ  
Key Inꢃut  
#
2
HEATINꢁ  
ON (ꢂ)  
HEATINꢁ  
ON (ꢂ2)  
COOꢀINꢁ  
ON (Y)  
COOꢀINꢁ  
ON (Y2)  
#2  
#12  
HEATINꢁ COOꢀ/HEAT COOꢀ/HEAT fAN ON  
O/B  
ON (ꢂ2)  
ON (Y)  
ON (Y2)  
(ꢁ)  
ON  
ON  
0
1
: Gas  
: Elec  
ON  
ON  
ON  
ON  
0 : Gas  
1 : Elec  
0 : Gas  
1 : Elec  
1
st [UP]  
1st [UP]  
ON  
ON  
#
50 Heat  
0 : Gas  
: Elec  
ON  
ON  
#50 Aux  
ON  
ON  
2
nd [UP]  
DOWN]  
st [UP]  
2nd [UP]  
2nd [UP]  
[DOWN]  
1
[
1
ON  
ON  
ON  
ON  
0 : O  
1 : B  
0 : O  
1 : B  
0 : O  
ON  
ON  
ON  
ON  
ON  
ON  
ON  
ON  
ON  
ON  
ON  
1
st [UP]  
2nd [UP]  
DOWN]  
st [UP]  
2nd [UP]  
#
51 Cool  
ON  
[
DOWN]  
UP]  
DOWN]  
ON  
ON  
#
51 Cool  
[
ON  
#
52 Fan  
[
[
1
0
1
0
1
0
1
: B  
: O  
: B  
: O  
: B  
: O  
: B  
ON  
ON  
ON  
ON  
ON  
ON  
ON  
ON  
1
ON  
ON  
ON  
ON  
ON  
#
52 Heat  
[
DOWN]  
UP]  
DOWN]  
[
ON  
#
53 Fan  
[
1
6
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QUICK REfERENCE TO CONTROꢀS & DISpꢀAY  
THERMOSTAT fEATURES  
Event-Based Air Cleaning.  
CURRENT INDOOR TEMPERATURE  
CURRENT TIME  
OUTDOOR TEMPERATURE (OPTIONAL)  
TEMPERATURE SETTING  
Large, clear, backlit display is easy to read – even in the dark.  
SYSTEM MODE  
SETTING  
• 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.  
EQUIPMENT STATUS  
UP  
CLEAN AIR  
SETTING  
SYSTEM MODE  
DOWN  
• Water panel and air filter service indicators.  
System test mode.  
• Separately programmable weekday/weekend schedules.  
CLEAN AIR  
HOLD  
PROGRAM  
HEAT pUMp ONꢀY  
Easy to use temperature control can override program schedule at any time.  
Includes Event-Based  
Air Cleaning  
EMERGENCY HEAT (RED)  
SYSTEM FAULT (YELLOW)  
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.  
INDICATOR SHOWS THROUGH HOUSING  
QUICK REFERENCE CARD  
BATTERY DOOR  
CURRENT SCHEDULE PERIOD  
MESSAGE CENTER  
LOW BATTERY WARNING  
NOTE: BACKLIGHT IS ACTIVATED WITH FIRST BUTTON PRESS AND AUTOMATICALLY TURNS OFF.  
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TROUBꢀESHOOTINꢁ  
TROUBꢀESHOOTINꢁ  
DISpꢀAY IS BꢀANK  
HEATINꢁ SYSTEM DOES NOT RESpOND  
“HEATINꢁ” AppEARS ON SCREEN)  
COOꢀINꢁ SYSTEM DOES NOT RESpOND  
(“COOꢀINꢁ” AppEARS ON SCREEN)  
HEAT/COOꢀ BOTH ON AT SAME TIME  
(
Check circuit breaker and reset if necessary.  
• Check SW1 (Equipment Type), to make sure it is set  
to match the installed heating/cooling equipment  
(see page 11)  
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 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.  
Make sure power switch at heating & cooling  
system is on  
Check to make sure heating and cooling wires are  
not shorted together  
Make sure furnace door is closed securely.  
If thermostat is battery powered, make sure fresh AA  
alkaline batteries are correctly installed  
• 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 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.  
HEATINꢁ EQUIpMENT IS RUNNINꢁ IN  
COOꢀ MODE  
TEMpERATURE SETTINꢁS DO NOT CHANꢁE  
Check SW1 (Equipment Type), to make sure it is set  
to match the installed heating/cooling equipment  
(see page 11)  
Check for loose or broken wires between the  
thermostat and the heating equipment.  
• Check for loose or broken wires between the  
thermostat and the cooling equipment.  
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).  
fAN DOES NOT TURN ON IN A CAꢀꢀ fOR HEAT  
HEATINꢁ” IS NOT DISpꢀAYED  
Check System Setting #02 (Fan Control), to make  
sure the fan control is properly set to match the type  
of system (see page 11)  
Change the System Mode to Heat, and set  
the temperature level above the current room  
temperature  
HEAT pUMp ISSUES COOꢀ AIR IN HEAT MODE,  
OR ꢂARM AIR IN COOꢀ MODE  
COOꢀINꢁ” IS NOT DISpꢀAYED  
Change the System Mode to Cool, and set  
the temperature level below the current room  
temperature  
Check System Setting #12 (Reversing Valve), to make  
sure it is properly configured for your system (see  
page 12)  
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SpECIfICATIONS  
SpECIfICATIONS  
Environment  
Thermal  
Operating: 32° to 120°F (0° to 48.9°C)  
Shipping: -30° to 140°F (-34.4° to 60°C)  
Outdoor temperature sensor  
Maximum distance: 300 feet  
Display range: 32° to 99°F (0° to 40°C)  
Display range: -20° to 130°F (-30° to 55°C)  
Temperature  
Room temperature measurement  
Outdoor temperature measurement  
Relative humidity  
Operating: 5% to 90% R.H. (non-condensing)  
Heat: 45° to 90°F (7° to 32°C)  
Cool: 50° to 99°F (10° to 37°C)  
Temperature setting range  
Electrical  
Operating voltage  
Current  
24 VAC (18 – 30 VAC)  
Maximum: 2.5A (total), 1.0A (single output)  
Maximum surge current: 5A  
Dual power. Can be battery or 24 VAC powered.  
Power supply  
When both the sources are available, battery will be used as  
back up power  
Battery power: AA size alkaline battery x 2  
Battery life: Approximately 1 year  
Battery power  
2
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P.O. Box 1467 • Madison, WI 53701-1467 • Phone: 800/334-6011 • Fax: 608/257-4357  
www.aꢃrilaireꢃartners.com  
6
1000893 12 11  
Patent Pending  
© 2011 Aprilaire – A division of Research Products Corporation  
B2205693A  
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