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®
ELECTRONIC THERMOSTATS  
MODEL 8353  
5
1
-2 Day Programmable  
Heat / 1 Cool  
Electric / Gas  
User’s Manual  
Installation and  
Programming  
Installation Guide  
IMPORTANT SAFETY INFORMATION WARNING:  
Always turn off power at the main power source by unscrewing  
fuse or switching circuit breaker to the off position before installing,  
removing, cleaning, or servicing thermostat.  
Read all of the information in this manual before installing or  
programming this thermostat.  
This is a 24V AC low-voltage thermostat. Do not install on voltages  
higher than 30V AC.  
All wiring must conform to local and national building and electrical  
codes and ordinances.  
Do not short (jumper) across terminals on the gas valve or at the  
system control to test installation. This will damage the thermostat  
and void the warranty.  
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Features  
Four setpoints for weekday programming—two setpoints for  
weekend comfort.  
Two “AA” ENERGIZER brand batteries retain program memory,  
even during power outages.  
Low battery indicator.  
Fahrenheit/Celsius display option.  
Programmable from 45°F (4°C) to 90°F (32°C).  
Accuracy within ± 1 degree.  
Adjustable temperature differential: 1-3 degrees.  
Maintains summer and winter programming.  
Low temperature freeze protection. While in heat mode, thermostat  
will mechanically turn on heat if temperature drops to 40°F (4°C) –  
even if batteries are missing or drained.  
Automatic heating shutdown if temperature exceeds 90°F (32°C).  
Replacing Existing Thermostat  
1. Turn off power to heating and cooling system.  
2. Remove cover of old thermostat to expose wires. Do not  
disconnect wires. (Fig. 1)  
3. Label wires per Table 1.  
Table 1  
Old Label  
New Label  
Description  
M, 4, RH, R5 or R  
V or RC  
RH  
Heat Transformer,  
hot side  
RC  
Cooling Transformer, hot  
side  
Y or Y6  
H, W or 4  
F or G  
C*  
Y
Cooling control  
Heating control  
Fan control relay  
W
G
Y or None  
Either cooling control or  
common side of trans-  
former  
*
NOTE: On some older models, the C terminal can be either the cooling-  
control or the common side of the transformer. Check furnace wiring  
diagram to verify C terminal. If it is the common side of the transformer,  
cap the wire and tuck into the wall. If it is the cooling control, connect to  
the Y terminal.  
4
5
6
. After labeling wires, remove wires from terminals.  
. Remove existing thermostat base from wall.  
. Refer to the following section for instructions on how to  
install thermostat.  
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Figure 1  
Installing the Model 8353 Thermostat  
NOTE: For new installations, mount thermostat on inside wall, 4-5 feet  
above the floor. Do not install behind a door, in a corner, near air vents,  
in direct sunlight, or near any heat or steam generating fixtures.  
Installation at these places will affect thermostat operation.  
1
. Turn power off to the heating and cooling systems.  
. Place COOL-OFF-HEAT In OFF position.  
2
COOL-OFF-HEAT  
PROG  
MAN  
SET PROG/MAN  
COOL-OFF-HEAT  
FAN: AUTO - ON  
FAN: AUTO-ON  
3. Place FAN: AUTO–ON switch  
Into AUTO position.  
4. Remove the cover using a coin  
or screwdriver.  
Figure 2  
5. Place thermostat against the wall at desired location. Make sure  
wires will feed through opening on base of thermostat.  
6. Mark placement of mounting holes. See Fig. 3. Set base aside.  
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Figure 3  
MOUNTING HOLES  
AM  
PM  
PROG  
RH  
RC  
MORN DAY EVE NITE  
MAN  
W
Y
CHANGE  
SET  
AUTO/MAN  
Elec  
Gas  
G
COOL OFF HEAT  
FAN AUTO ON  
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. Drill the marked holes using a 3/16” drill bit. Note: Enclosed plastic  
anchors do not require a drilled hole for drywall.  
8. Tap plastic anchors into the wall.  
9. Align base with plastic anchors and feed wires through opening.  
See Fig 4.  
Figure 4  
AM  
PM  
PROG  
RH  
RC  
MORN DAY EVE NITE  
MAN  
W
Y
CHANGE  
SET  
AUTO/MAN  
Elec  
Gas  
G
COOL OFF HEAT  
FAN AUTO ON  
10. Secure base to wall with supplied screws.  
11. Connect wires to terminal strip. Refer to wiring diagrams on other  
side of this sheet. Make sure wire connections are secure.  
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2. Place fan option switch into either the “ELEC” or “GAS” position  
depending upon the type of furnace. Refer to Figure 5.  
Figure 5  
AM  
PM  
PROG  
FAN  
RH  
RC  
OPTION  
SWITCH  
Controls  
fan delay.  
MORN DAY EVE NITE  
MAN  
W
Y
CHANGE  
SET  
AUTO/MAN  
Elec  
Gas  
G
COOL OFF HEAT  
FAN AUTO ON  
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3. Install two “AA” ENERGIZER brand batteries or equivalent into  
battery compartment. Be sure to match positive (+) ends of batteries  
with positive (+) battery terminals in the battery compartment. The  
display will show as follows:  
14. Replace cover onto thermostat by snapping into place.  
15. Turn on power to system . Test thermostat as described in the  
following section.  
Programming Guide  
Set Time of Day, Day of Week,  
Temperature Differential  
1
. Press & Hold SET. Press PROG/MAN  
Release simultaneously.  
SET PROG/MAN  
PROG  
MAN  
SET PROG/MAN  
COOL-OFF-HEAT  
FAN: AUTO - ON  
2. Press or to change  
Time of Day.  
3. Press  
4. Press  
SET  
1
2
3
4
5
6
7
=MO  
=TU  
=WE  
=TH  
=FR  
=SA  
=SU  
To Change  
Day of Week  
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5. Press  
6. Press  
SET  
P
To change  
Temperature Differential*  
*
The Temperature Differential is Factory preset at 1°. This means that  
whenever the room temperature changes by one full degree from the  
temperature setting, the system will turn on. If the system turns on too  
often, increase the temperature differential.  
7. Press SET to finish.  
Changing Fahrenheit (F) to Celsius (C)  
Press and Hold SET  
Press  
SET  
P
Release both simultaneously.  
Setting Daily Programming  
1
. Place COOL-OFF-HEAT switch  
in COOL position.  
COOL-OFF-HEAT  
PROG  
MAN  
SET PROG/MAN  
COOL-OFF-HEAT  
FAN: AUTO - ON  
SET PR  
2. Press SET.  
3
. Press  
or  
to change  
MORN time in 30-minute  
intervals.  
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4. Press SET.  
SET PR  
PROG  
MAN  
SET PROG/MAN  
COOL-OFF-HEAT  
FAN: AUTO - ON  
5. Press or to change  
MORN temperature.  
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7
8
. Repeat Steps 2-5 for DAY, EVE, and NITE.  
COOL-OFF-HEAT  
. Press SET to finish.  
. Shift COOL-OFF-HEAT switch to  
HEAT position.  
9. Repeat steps 2-7 to program HEAT (winter) settings.  
NOTE: Both summer and winter programs use the same time settings.  
Your thermostat is now programmed for summer and winter operation.  
It will follow the four settings (MORN, DAY, EVE, NITE) for weekday  
operation and two settings (MORN and NITE) for weekend operation.  
Adjust the program at any time by following the steps as outlined above.  
Begin Programmed Operation  
1
. Place FAN: AUTO–ON switch  
FAN: AUTO-ON  
Into AUTO.  
PROG  
MAN  
SET PROG/MAN  
COOL-OFF-HEAT  
FAN: AUTO - ON  
COOL-OFF-HEAT  
SUMMER  
WINTER  
2
. Place COOL-OFF-HEAT switch  
Into COOL or HEAT  
Depending upon the season.  
COOL-OFF-HEAT  
3. Press PROG/MAN button  
until indicator is in PROG position.  
ET PROG/MAN  
PROG  
MAN  
SET PROG/MAN  
COOL-OFF-HEAT  
FAN: AUTO - ON  
PROG  
MAN  
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Temporary Program Override  
To temporarily increase or decrease temperature  
Press or  
PROG  
MAN  
SET PROG/MAN  
COOL-OFF-HEAT  
FAN: AUTO - ON  
The thermostat will automatically return  
to the program at the next scheduled  
setting change or after four hours.  
Manual Operation  
Manual operation allows continuous override of the program settings.  
1. Press PROG/MAN until indicator is in MAN position.  
PROG  
MAN  
PROG  
MAN  
T
PROG/MAN  
SET PROG/MAN  
COOL-OFF-HEAT  
FAN: AUTO - ON  
2
. Press or to adjust  
temperature settings.  
Reset  
To reset the thermostat to factory pre-programmed  
conditions, press the reset button located directly  
to the right of the display.  
RESET  
BUTTON  
AM  
PM  
PROG  
RH  
RC  
MORN DAY EVE NITE  
MAN  
W
Y
CHANGE  
SET  
AUTO/MAN  
Elec  
Gas  
G
COOL OFF HEAT  
FAN AUTO ON  
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To Test Thermostat  
WARNING: DO NOT SHORT (JUMPER) ACROSS TERMINALS OF GAS  
VALVE OR SYSTEM CONTROL TO TEST OPERATION. THIS WILL DAM-  
AGE THE THERMOSTAT AND VOID YOUR WARRANTY.  
CAUTION: Do not switch system to cool if the temperature is below  
5
0°F (10°C). This can damage the air conditioning system and cause  
personal injury.  
COOL-OFF-HEAT  
1. Place the COOL-OFF-HEAT  
switch into the COOL position  
2
. Press the button until the temperature  
setting is at least 3 degrees below the room temperature. The  
air conditioning system should turn on within a few seconds.  
NOTE: There is a built in 5-minute delay on break for compressor  
protection. A second attempt to turn on the air conditioning will  
result in a 5-minute delay in compressor activation.  
COOL-OFF-HEAT  
3
. Put the COOL-OFF-HEAT switch into  
the OFF position. The air conditioning  
system should turn off. The fan may  
continue to run for a short period of time.  
COOL-OFF-HEAT  
4. Put the COOL-OFF-HEAT switch  
into the HEAT position.  
5
. Press the button until the temperature setting is at least  
degrees above room temperature. The heating system should  
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turn on. The fan may not turn on immediately, depending upon  
the fan delay built into the furnace.  
6
. Put the COOL-OFF-HEAT switch  
into the OFF position. The heating  
system should turn off. Once again,  
the fan may have a delay.  
COOL-OFF-HEAT  
7
. Put the FAN: AUTO–ON switch  
to the ON position. The blower  
fan should turn on.  
FAN: AUTO - ON  
FAN: AUTO-ON  
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. Put the FAN: AUTO–ON switch  
to the AUTO position. The blower  
fan should turn off.  
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Troubleshooting  
Symptom  
Remedy  
Thermostat does not turn  
on system  
Check Wiring  
(see INSTALLATION).  
Check fuse. Replace with 2 amp  
Slo-Blo fuse if fuse has opened.  
Thermostat turns on and off too  
frequently.  
Increase Temperature Differential  
(see PROGRAMMING).  
Display is blank, flashing or  
constant “LO BAT.”  
Replace batteries.  
Weekend Program follows four  
adjustment settings.  
Verify that day of week is set  
correctly (see PROGRAMMING).  
System fan does not operate  
properly.  
Move fan option switch to either  
gas or electric, to match system  
(see INSTALLATION).  
Time shown on display is not the  
current time of day.  
Change time of day setting  
(see PROGRAMMING).  
Thermostat does not  
follow program.  
Thermostat in MANUAL mode  
(see PROGRAMMING).  
Thermostat may not have been  
programmed in HEAT or COOL  
position. Verify program.  
Check AM/PM indicators at time  
of day and programmed time  
changes (see PROGRAMMING).  
Verify program and day of week  
is correct (see PROGRAMMING).  
If problems with thermostat cannot be solved, call:  
Technical Support: 608-257-8801  
Monday-Friday 7:45 am - 5:00 pm CST  
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Wiring Diagrams  
The following is just a sample of the most common types of HVAC sys-  
tems. Refer to your systems installation manual for wiring information.  
HEAT  
/COOL  
HEAT ONLY  
3-WIRE  
SINGLE TRANSFORMER  
4
-WIRE  
SINGLE TRANSFORMER  
Factory-Installed  
jumper  
Factory- Installed  
jumper  
T
T
RH  
RH  
Transformer  
Hot  
H
E
R
M
O
S
T
Transformer  
Hot  
H
E
R
M
O
S
T
RC  
W
RC  
W
1
20 VAC  
24 VAC  
120 VAC  
24 VAC  
Heating  
Control  
Heating  
Control  
Cooling  
Control  
Y
Y
A
T
Fan  
Control  
A
T
Fan  
Control  
G
G
HEAT ONLY  
2
-WIRE  
COOL ONLY  
SINGLE TRANSFORMER  
3
-WIRE  
SINGLE TRANSFORMER  
NOTE: Remove factory  
installed jumper  
NOTE: Remove factory  
installed jumper  
T
H
RH  
T
H
RH  
Transformer  
Hot  
Transformer  
Hot  
RC  
W
E
R
M
O
S
T
RC  
W
E
R
M
O
S
T
1
20 VAC  
24 VAC  
Heating  
Control  
120 VAC  
24 VAC  
Y
Cooling  
Control  
Y
A
T
G
Fan  
Control  
A
T
G
HEAT  
-WIRE  
TWO TRANSFORMER  
/COOL  
5
(
HEATING)  
NOTE: Cut center of  
factory installed jumper  
and bend back  
Transformer  
Hot  
T
H
E
R
M
O
S
T
RH  
RC  
1
20 VAC  
24 VAC  
NOTE: Both transformers  
must be in phase.  
Heating  
Control  
W
Y
Cooling  
Control  
Hot  
20 VAC  
1
24 VAC  
Fan  
Control  
A
T
G
(
COOLING)  
Transformer  
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Limited Warranty  
®
Your Research Products Corporation Aprilaire Thermostat unit is expressly  
warranted for two (2) years from date of installation to be free from defects in  
materials and 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 a two (2) year period and which is returned, together with  
the date of installation, no later than thirty (30) days after said two (2) year  
period by you to either your original supplier or to Research Products  
Corporation, Madison, Wisconsin 53701.  
THIS WARRANTY SHALL NOT OBLIGATE RESEARCH PRODUCTS CORPO-  
RATION FOR ANY LABOR COSTS AND SHALL NOT APPLY TO DEFECTS IN  
WORKMANSHIP OR MATERIALS FURNISHED BY YOUR INSTALLER AS CON-  
TRASTED TO DEFECTS IN THE THERMOSTAT ITSELF.  
IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PAR-  
TICULAR PURPOSE SHALL BE LIMITED IN DURATION TO THE AFORESAID  
TWO YEAR PERIOD. RESEARCH PRODUCTS CORPORATION’S LIABILITY  
FOR INCIDENTAL OR CONSEQUENTIAL DAMAGES, OTHER THAN DAMAGES  
FOR PERSONAL INJURIES, RESULTING FROM ANY BREACH OF THE AFORE-  
SAID 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 exclusion 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.  
P.O. BOX 1467 • MADISON, WI 53701-1467  
Products For Better Indoor Air Quality  
B2202517 REV. 12/00  
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