Aprilaire Thermostat 8535 User Manual

110-965B 7/12/01 9:12 AM Page 1  
®
ELECTRONIC THERMOSTAT  
Owners Manual  
MODELS  
8535, 8536 & 8537  
Digital Heat Pump Thermostats  
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IMPORTANT: READ ALL INSTRUCTIONS THOROUGHLY  
Introduction  
Thank you for your recent Aprilaire® Electronic Thermostat purchase. We sincerely  
appreciate your business and are pleased to add your name to our growing list of customers.  
With this purchase, you have invested in the highest quality equipment currently available.  
Please be assured that in addition to product quality, we are committed to total product  
performance and complete customer satisfaction.  
Now, please take a few minutes to familiarize yourself with your new Aprilaire Thermostat.  
In order to take advantage of all the benefits of your new thermostat, it is important that you  
understand how to operate it.  
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110-965B 7/12/01 9:12 AM Page 4  
Aprilaire  
Digital Heat Pump Thermostat  
Center LED illuminates  
when back-up heat  
source is being used.  
(Models 8536 & 8537  
only)  
Temperature ˚F or ˚C.  
Room temp. normally  
displayed. Press  
Outdoor button to  
display outdoor temp.  
(Model 8041 required).  
Heat and Cool Mode  
icons. Both displayed  
during Auto Mode.  
Flame flickers during  
heat call and Snowflake  
flashes during cool call.  
Set-point icon displays  
the active set point  
(full sun = Day set  
point, partial moon  
= Night set point).  
Displays mode when  
changing (Heat, Cool,  
Emergency Heat, Off,  
and Auto). (Emergency  
Heat Models 8536 &  
8537 only)  
Mode  
Fan  
Outdoor  
Day/Night  
Press to select Heat/  
Emergency Heat/Cool/  
Auto/Off. (Emergency  
Heat Models 8536  
& 8537 only)  
Press to display  
outdoor temperature  
(w/optional Model 8041  
Remote Outdoor  
Sensor only).  
Press for continuous  
fan. Press again to  
resume to auto fan.  
Press to change  
set point to either  
the Day or Night  
preset value.  
Press to raise and lower set point. Press both at the  
same time to switch between ˚F and ˚C. Press and  
release to view current set point.  
Fan icon displays during  
continuous fan only.  
Figure 1 - Display and Button Description  
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110-965B 7/12/01 9:12 AM Page 5  
Getting Familiar with the Aprilaire Thermostat  
(refer to Figure 1)  
The LCD (Liquid Crystal Display) normally shows: the room temperature, the current mode of operation, if  
the Day or Night temperature setting is being used, and if the system fan is set for continuous operation.  
Temperature Display  
Room temperature can be displayed in either degrees Fahrenheit or degrees Celsius. If the displayed  
temperature seems abnormally high or low (example: 70˚F is equal to 21˚C), press the DECREASE  
button and INCREASE  
button simultaneously to switch between ˚F and ˚C.  
Mode Button  
Four modes of operation are available for all the DSL heat pump thermostat models: Heat, Cool, Auto,  
and Off. Additionally, with the Models 8536 and 8537, Emergency Heat mode is available. The mode of  
operation indicates how you want your heating and cooling equipment to operate. Press the MODE  
button until the desired mode of operation shows on the display.  
Temperature Settings - Day/Night Button  
The thermostat stores four temperature settings in its memory, two for heating (Emergency Heat uses the  
same set points as the Heat mode) and two for cooling. The two temperatures for each mode are called  
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the Day setting ”  
“ (a sun icon appears on the display) and the Night setting “ “ (a moon icon  
appears on the display). The Day setting is intended to be an occupied or comfort setting and the Night  
setting is intended to be an unoccupied or energy savings setting. For example the four settings stored  
in the memory of the thermostat might be as shown in Table 1. Pressing the DAY/NIGHT button allows  
you to instantly change to a more economical setting when leaving the house or going to bed, and to  
a comfort setting when returning home or waking up. This  
MODE  
Heat  
DAY  
68˚F  
78˚F  
NIGHT  
60˚F  
thermostat is equipped with accessory inputs which can be used  
to automatically switch between day and night set points; contact  
your installing contractor for more details.  
Cool  
85˚F  
Table 1 – Typical Set Point Values  
Fan Button  
The system fan will operate automatically during a heating or cooling cycle. If it is desired to run the fan  
continuously, press the FAN button, and a Fan “  
“ icon will appear on the display.  
Outdoor Button  
This button will be made functional when the optional Aprilaire Model 8041 Remote Outdoor Sensor has  
been installed. It can then be used to find out the outdoor temperature from indoors. If the Model 8041  
Remote Outdoor Sensor has not been installed, two dashes “– –” will appear on the display when this  
button is pushed.  
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Setting Up The Aprilaire Thermostat  
To ensure accurate temperature control, observe the following simple guidelines:  
When the thermostat is operating, close the cover to allow proper air circulation over the  
temperature sensor.  
Do not place anything which can give off warm or cool air, such as candles or portable humidifiers,  
near the thermostat.  
1. Adjusting the Heat Temperature Settings. There are  
two settings, the Day setting “  
“ (a sun icon  
appears on the display) and the Night setting “  
(a partial moon icon appears on the display).  
See Figure 2.  
a. Press the MODE button repeatedly until HEAt  
appears on the display.  
b. Press the DAY/NIGHT button until the “  
(Day setting) appears on the display.  
“ icon  
c. Use the DECREASE  
button and INCREASE  
DAY  
NIGHT  
button to adjust the setting.  
Figure 2 - Adjust Heat Settings  
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d. Press the DAY/NIGHT button until the “ “ icon (Night setting) appears on the display.  
e. Use the DECREASE  
button and INCREASE  
button to adjust the setting.  
2. Adjusting the Cool Temperature Settings. There are two  
settings, the Day setting “ “ (a sun icon appears on  
the display when this setting is being used) and the Night  
setting “ “ (a partial moon icon appears on the display  
when this setting is being used). See Figure 3.  
a. Press the MODE button repeatedly until COOL  
appears on the display.  
b. Press the DAY/NIGHT button until the “  
(Day setting) appears on the display.  
“ icon  
c. Use the DECREASE  
button and INCREASE  
DAY  
NIGHT  
Figure 3 - Adjust Cool Settings  
button to adjust the setting.  
d. Press the DAY/NIGHT button until the “ “ icon (Night setting) appears on the display.  
e. Use the DECREASE  
button and INCREASE  
button to adjust the setting.  
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Operating The Aprilaire Thermostat  
1. Select the mode of operation by repeatedly pressing the MODE button until the desired mode  
appears on the display (“E ht” = Emergency Heat – Models 8536 and 8537 only). The heating and  
cooling system may be turned off by selecting the “OFF” mode. Do not set to the “OFF” mode  
during periods when freezing temperatures may occur.  
COOL: In the “COOL” mode a Snowflake “  
“ icon appears on the display, which flashes  
when the heat pump is running.  
HEAT: In the “HEAt” mode a Flame “ “ icon appears on the display, which flickers when the  
heat pump is running.  
EMERGENCY HEAT (Models 8536 and 8537 only): In the Emergency Heat mode, “E ht” appears on  
the display and only the back-up heat source (other than the heat pump) will be used to maintain  
temperature. The center LED (located at the top of the thermostat) will light when the back-up  
heat source is running.  
AUTO: In the “AUtO” mode, the heat pump will operate in either the “HEAt” or “COOL” mode  
depending on which current setting the room temperature is closest to. Note that both the  
Snowflake “  
“ and Flame “ “ icons appear on the display.  
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2. Select the temperature setting to be used by pressing the DAY/NIGHT button until the  
desired previously stored temperature setting (Day or Night) appears on the display. Use the  
DECREASE  
button and INCREASE  
button to change the temperature if desired (NOTE  
that if changed, the new set point will be permanently stored in memory - see CHANGING THE  
CURRENT TEMPERATURE SETTING).  
3. After approximately 5 seconds the thermostat will return to the normal display.  
Note: This thermostat utilizes time delays to protect the heating and cooling equipment. If the  
equipment does not shut off or turn on immediately when the temperature setting has been  
changed, it may be due to the built-in time delays (4 minutes max.).  
4. Press the Fan button, if it is desired, to run the fan continuously. A Fan “  
“ icon will appear  
on the display when the fan is set to operate continuously.  
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Changing The Current Temperature Setting  
1. Press and release either the DECREASE  
button or INCREASE  
button to see the current  
temperature setting. The setting, a Thermometer icon and a Double Arrowhead icon will appear  
(see Figures 2 and 3 on pages 5 and 6).  
2. Change the temperature setting:  
OPTION 1 – Use the DECREASE  
button or INCREASE  
button. Press and hold the  
DECREASE button or INCREASE  
button to change the current temperature setting. The  
thermostat remembers the most recent temperature settings. For example, if the Day, Cool  
temperature shown in Figure 3 were changed from 78˚F to 76˚F, the 76˚F setting would remain in  
memory as the Day, Cool setting.  
Note: The Cool temperature setting must remain 2˚F higher than the Heat temperature setting for  
both the Day and Night sets. The thermostat will automatically update the setting not being  
changed. In the example above, if the Day, Heat setting was 75˚F, the thermostat would have  
automatically changed the setting to 74˚F when the Cool setting was changed to 76˚F.  
OPTION 2 – Use the DAY/NIGHT button. Press the DAY/NIGHT button to instantly change the  
temperature setting to one of the two settings stored in memory.  
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110-965B 7/12/01 9:12 AM Page 12  
Optional Feature – Locking The Keypad  
If tampering with the thermostat is expected and unwanted, the keypad can be locked by changing the  
position of the Keypad Lock DIP switch (switch no.4) from the factory set OFF position to ON.  
The DIP switches are located inside the thermostat on the circuit board. To access the DIP switches,  
refer to the Installation Instructions that came with the thermostat, or consult your contractor.  
In the locked position, only the following functions can be done:  
The outdoor temperature button will display the outdoor temperature.  
The thermostat will default to the Day setting.  
The DECREASE  
button and INCREASE  
button will temporarily change the Day setting  
a maximum of ±6°F (±3°C) for a period of 3 hours before the thermostat automatically returns to  
the Day setting.  
If the thermostat does not respond when a button is pushed, it may be because the keypad has been  
locked. A Lock “ “ icon will appear when a button other than Outdoor is pushed if the keypad has  
been locked.  
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110-965B 7/12/01 9:12 AM Page 13  
Setting High And Low Balance Points  
(Models 8536 & 8537 only)  
High and low balance points can only be accessed if the Aprilaire Model 8041 Remote Outdoor Sensor  
has been installed. To check if this optional accessory has been installed, press the Outdoor button. If a  
temperature appears, the Model 8041 Remote Outdoor Sensor has been installed.  
During heating, heat pumps operate by extracting energy out of the outdoor air and transferring it to  
the indoor air. This process is efficient over a wide range of temperatures. However, at low outdoor  
temperatures there is a point at which it becomes more economical to operate the back-up heat without  
the heat pump. This is called the Low Balance Point,“Lo bP. Conversely, the use of back-up heat with  
the heat pump during mild weather could use more energy than is required to heat the home. At  
outdoor temperatures exceeding the High Balance Point,“Hi bP, use of the back-up heat is limited  
to Emergency Heat operation only.  
To review the set points, press and hold the Outdoor button and press the Fan button. “Hi bP” and its  
temperature value will appear on the display. Next, press the Outdoor button again and “Lo bP” and  
its temperature value will appear on the display. After approximately 15 seconds the display will return  
to normal.  
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110-965B 7/12/01 9:12 AM Page 14  
After accessing a balance point, it can be changed by pressing the DECREASE  
button or  
INCREASE  
button. This should only be done after consulting with a qualified contractor. Improperly  
set balance points can result in increased energy expenses and possible equipment damage.  
In Case Of Power Failure  
This thermostat does not require a battery. If the power goes out, the display is blank. During the  
period that the power is off, the heating/cooling system will not operate. When the power is restored,  
the thermostat will default to the Day setting and the current mode of operation at the time of the  
power outage.  
This thermostat is equipped with a continuous memory feature which does not require any battery.  
The thermostat will never lose the four programmed temperature settings regardless of the length of  
the power outage.  
Cleaning  
If the surface of the thermostat becomes dirty it can be cleaned with plain water or many non-abrasive  
household cleaners, such as glass cleaner. When using any cleaner be careful not to get any into the  
interior of the thermostat. Do not spray any cleaner directly onto the thermostat. Spray the cleaner onto  
a soft cloth and wipe the surface of the thermostat.  
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110-965B 7/12/01 9:12 AM Page 15  
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 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 OR FITNESS FOR A PARTICULAR PURPOSE SHALL  
BE LIMITED IN DURATION TO THE AFORESAID TWO YEAR PERIOD. RESEARCH PRODUCTS CORPORATIONS  
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 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.  
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110-965B 7/12/01 9:12 AM Page 16  
The Aprilaire® Total Indoor Air Comfort System is an integrated group of air quality enhancement  
products designed to work with your heating and cooling system to make your home more comfortable.  
For the best in indoor air quality, ask your heating and cooling contractor about these fine  
Aprilaire products, or visit us at www.aprilaire.com for your Indoor Air Solutions.  
Automatic Humidifier  
High Efficiency Air Cleaner  
Fresh Air Exchanger  
The Best Cure For Dryness®  
Nobody Makes Clean Air Easier®  
Only The Freshest Homes Have April Air™  
The worlds first computer-equipped,  
completely automatic humidifier.  
The economical, trouble-free, high  
efficiency air cleaner for your home. supply of fresh air with energy-recovery.  
Your best value for a constant, controlled  
Zone Control System  
Electronic Thermostat  
Custom Comfort Throughout Your Home®  
Energy Efficiency Never Looked So Good™  
The most reliable way to achieve temperature  
control in every area of your home.  
Ultra-thin, easy-to-use programmable or digital  
controls featuring pinpoint accuracy.  
P.O. BOX 1467 MADISON, WI 53701-1467  
Products For Better Indoor Air Quality™  
B2202210 REV. 04/01  
110-965B  
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