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The model 8539 is a single-setpoint heat/cool ther-
mostat. It features a narrow, fixed deadband between
internal heat and cool setpoints.
USER CONTROLS
COOLER
To lower the temperature in the zone, press and hold
the ✞ button until the desired temperature is dis-
played, then release.
WARMER
To raise the temperature in the zone, press and hold
the ✟ button until the desired temperature is dis-
played, then release.
The number that is displayed when the button is
released is the new setpoint or control temperature
for the zone. The display will return to the normal
room temperature display after a few seconds.
CELSIUS/FAHRENHEIT
Simultaneously press ✞
and ✟ to switch between
Celsius and Fahrenheit temperature display.
SEE REVERSE FOR INSTALLATION INSTRUCTIONS
Your new digital thermostat has been designed to
provide accurate control and display of room temper-
ature. In addition, it also will display all relevant infor-
mation pertaining to your system.
The clearly marked buttons and informative display
make it extremely easy to understand and simple to
use.
Please take a few moments to read the brief instruc-
tions and familiarize yourself with the various func-
tions in order to obtain maximum benefit from this
truly unique electronic control.
GENERAL INFORMATION
The thermostat normally displays room temperature,
mode of operation and whether cooling or heating is
currently on. The two buttons on the front of the unit
allow complete control of the equipment.
Raising or lowering the setpoint is as simple as push-
ing a button. In addition, you may choose to display
the temperature in °F or °C.
The thermostat also allows you to select continuous
fan operation (useful when using an air cleaner) or
have the fan come on with the equipment.
USER CONTROLS (Cont’d)
HEAT & COOL INDICATION ON DISPLAY
When the equipment is off, both flame and
snowflake are on steadily. When the thermostat is
calling for heat, the flame flickers and the snowflake
goes off. When cooling, the snowflake flickers and
the flame goes off.
LIMITED OVERRIDE
When the keyboard is locked (DIP switch #2 ON),
the user may override the temperature setpoint for 1
hour by pressing either the ✞ or ✟ button. The
range of temperature override is ±6°F or ±3°C from
the programmed daytime setpoint.
NOTES
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Model 8539 111-172B 97185
8539
Single Setpoint Heating & Cooling
Auto Changeover with Reversing Valve
OPERATING INSTRUCTIONS
USER CONTROLS (Cont’d)
FAN
$
The fan will come on automatically when the system
is operating, but there is no indication of this on the
display. To select continuous fan operation, press
the FAN button and the display will show
$
. This
is recommended for electronic air cleaners or con-
tinuous ventilation requirements.
NOTE: For fan coil applications in which the O and
B output terminals control valve position, DO NOT
use continuous fan.
REMOTE SENSOR (OPTION)
RS1 – RS2 – RS+V
The thermostat is designed to accept the electronic
remote sensor, which will allow you to locate your
thermostat in an area away from view. Indoor and
outdoor sensors are available separately.
POWER FAILURES
Your thermostat employs the latest developments in
solid state electronic technology.
One of the unique features of your thermostat is that
no battery is required to maintain your selected set-
points in the event of a power loss as the memory is
unaffected by power failures of any duration.
When power is restored, the thermostat will continue
operating as if the power had never been off.
TEMPERATURE ACCURACY
Full temperature accuracy will be realized only after
the thermostat has been installed and powered for
at least one hour.
ELECTRONIC PROGRAMMABLE THERMOSTAT
TWO YEAR LIMITED WARRANTY
Your Research Products Corporation Aprilaire
®
Thermostat unit is
expressly warranted for two (2) years from the date of installation to be
free from defects.
Research Products Corporation’s exclusive obligation under this war-
ranty shall be to supply, without charge, a replacement for any thermo-
stat which is found to be defective within a two (2) year period and
which is returned 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, together with the model num-
ber, manufacturing code number and installation date of the thermostat.
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 PARTIC-
ULAR PURPOSE SHALL BE LIMITED IN DURATION TO THE AFORESAID TWO
(2) YEAR PERIOD. RESEARCH PRODUCTS CORPORATION’S 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 UNIT 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 dam-
ages 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.
This equipment if installed in strict accordance with the manufacturers
instructions,complies with the limits for a Class B computing device pur-
suant to Subpart J of Part 15 of FCC rules.
111-172B