Page 1
Installation Instructions for
Heating & Cooling
Digital Model 850
5/1/1 Day Programmable
Thermostat
CONTENTS
Preparations.................................................. 1
Thermostat Details ........................................ 1
Removing Old Thermostat ............................ 1
Mounting and Wiring ..................................... 2
Check Thermostat Operation........................ 4
Specifications ................................................ 7
Troubleshooting ............................................ 7
Y OUR THERMOST AT REPLACES
Description 850
Standard Heat & Cooling Systems – 4 or 5 wires Yes
Standard Heat Only Systems Yes
Millivolt Heat Only Systems – Floor or Wall Furnaces Yes
Standard Central Air Conditioning Yes
Gas or Oil Heat Yes
Electric Furnace Yes
Hydronic (Hot Water) Zone Heat – 2 Wires Yes
Hydronic (Hot Water) Zone Heat – 3 Wires No
Heat Pump (No Aux or Emergency Heat) Yes
Heat Pump (with Aux or Emergency Heat) No
Baseboard Electric Heating or Line Voltage (120 or 240 volt) No
THERMOSTAT DETAILS
2
Screw anchors
PREPARATIONS
1
Assemble tools required as shown below.
FLAT BLADE SCREWDRIVER
HAND OR POWER
DRILL WITH 3/16 INCH
DRILL BIT, IF NEEDED
SPIRIT LEVEL OR PLUMB BOB AND LINE (OPTIONAL)
Failure to follow and read all instructions carefully
before installing or operating this control could cause
personal injury and/or property damage.
REMOVING OLD THERMOSTAT
3
CAUTION
!
To prevent electrical shock and/or equipment damage,
disconnect electrical power to the system at the main
fuse or circuit breaker until installation is complete.
WIRE CUTTER/STRIPPER
Mounting
holes
Electric/Gas
switch
Figure 1. Thermostat base
Mounting
holes
Before removing wires from old thermostat’s switching subbase,
label each wire with the terminal designation it was removed from.
1. Remove Old Thermostat: A standard heat/cool thermostat
consists of three basic parts:
a. The cover, which may be either a snap-on or hinge type.
b. The base, which is removed by loosening all captive screws.
c. The switching subbase, which is removed by unscrewing
the mounting screws that hold it on the wall or adaptor plate.
2. Shut off electricity at the main fuse box until installation is
complete. Ensure that electrical power is disconnected.
3. Remove the front cover of the old thermostat. With wires still
attached, remove wall plate from the wall. If the old thermostat
has a wall mounting plate, remove the thermostat and the wall
mounting plate as an assembly.
4. Identify each wire attached to the old thermostat using the
labels enclosed with the new thermostat.
5. Disconnect the wires from the old thermostat one at a time. DO
NOT LET WIRES FALL BACK INTO THE WALL.
6. Install new thermostat using the following procedures.
White-Rodgers is a division
of Emerson Electric Co.
www.white-rodgers.com
PART NO. 37-6295B
Replaces 37-6295A
0514
Page 2
REMOVING OLD THERMOSTAT
TERMINAL CROSS REFERENCE CHART
New Thermostat
Terminal Designation
Other Manufacturers’
Terminal Designation
RH
RC
G
W
Y
4
R
G
W
Y
RH
R
G
W
Y
M
V
F
H
C
R5
-
G
4
Y6
R
-
G
W
Y
**
* These are four-wire, single-transformer systems.
Factory installed jumper wire between the RH
and RC terminals must remain in place.
3
CONTINUED FROM FIRST PAGE
ATTENTION! This product does not contain mercury. However, this product may replace a unit which contains mercury.
Do not open mercury cells. If a cell becomes damaged, do not
touch any spilled mercury. Wearing non-absorbent gloves, take
up the spilled mercury and place into a container which can be
sealed. If a cell becomes damaged, the unit should be discarded.
Mercury must not be discarded in household trash. When the unit
this product is replacing is to be discarded, place in a suitable
container and return to White-Rodgers for proper disposal.
MOUNTING AND WIRING
4
WARNING
!
Do not use on circuits exceeding specified voltage.
Higher voltage will damage control and could cause
shock or fire hazard.
Do not short out terminals on gas valve or primary
control to test. Short or incorrect wiring will damage
thermostat and could cause personal injury and/or
property damage.
Thermostat installation and all components of the system shall conform to Class II circuits per the NEC code.
Electric Heat or Single Stage
Heat Pump Systems
This thermostat is configured from the factory to operate a heat/
cool, fossil fuel (gas, oil, etc.), forced air system. It is configured
correctly for any system that DOES NOT require the thermostat
to energize the fan on a call for heat. If your system is an electric
or heat-pump system that REQUIRES the thermostat to turn on
the fan on a call for heat, locate the GAS/ELECTRIC switch (see
fig. 1) and switch it to the ELECTRIC position. This will allow the
thermostat to energize the fan immediately on a call for heat. If you
are unsure if the heating/cooling system requires the thermostat
to control the fan, contact a qualified heating and air conditioning
service person.
Hydronic (Hot Water or Steam)
Heating Systems
This thermostat is set to operate properly with a forced-air heating
system. If you have a hydronic heating system (a system that
heats with hot water or steam), you must set the thermostat to
operate properly with your system. Change the second option in
the configuration menu to SL (see CONFIGURATION MENU,
page 5).
CAUTION
!
Take care when securing and routing wires so they do
not short to adjacent terminals or rear of thermostat.
Personal injury and/or property damage may occur.
Attach Thermostat Base to Wall
1. Remove the packing material from the thermostat. Gently pull
the cover straight off the base. Forcing or prying on the
thermostat will cause damage to the unit. If necessary, move
the electric heat switch (see ELECTRIC HEAT SYSTEMS,
above).
2. Connect wires beneath terminal screws on base using appropriate wiring schematic (see figs. 2 through 7).
3. Place base over hole in wall and mark mounting hole locations
on wall using base as a template.
4. Move base out of the way. Drill mounting holes.
5. Fasten base loosely to wall, as shown in fig. 1, using two
mounting screws. Place a level against bottom of base, adjust
until level, and then tighten screws. (Leveling is for appearance only and will not affect thermostat operation.) If you are
using existing mounting holes, or if holes drilled are too large
and do not allow you to tighten base snugly, use plastic screw
anchors to secure base.
6. Push excess wire into wall and plug hole with a fire-resistant
material (such as fiberglass insulation) to prevent drafts from
affecting thermostat operation.
Battery Location
This thermostat requires 2 “AA” alkaline batteries to operate. If the
word LO BATTERY is displayed, the batteries are low and should
be replaced with fresh “AA” Energizer® alkaline batteries. To
replace the batteries, install the batteries along the top of the base
(see fig. 1). The batteries must be installed with the positive(+)
ends to the right.
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Page 3
MOUNTING AND WIRING
RH
Y
24 VAC
120 VAC
Hot
Neutral
THERMOSTAT
SYSTEM
G W
Figure 5. Typical wiring diagram for
heat/cool, 5-wire, two-transformer systems
HEATING
TRANSFORMER
Heating
System
Fan
Relay
Cooling
System
RC
24 VAC
120 VAC
Hot
Neutral
COOLING TRANSFORMER
OBC
‡
RH
Y
24 VAC
120 VAC
Hot
Neutral
THERMOSTAT
SYSTEM
G W
Figure 6. Typical wiring diagram for heat pump
with reversing valve energized in COOL
TRANSFORMER
Reversing
Valve*
RCOBC
‡
JUMPER
WIRE
Compressor
Contactor
JUMPER
WIRE
* Reversing valve is energized when the
system switch is in the COOL position
Fan
Relay
RH
Y
24 VAC
120 VAC
Hot
Neutral
THERMOSTAT
SYSTEM
G W
Figure 7. Typical wiring diagram for heat pump
with reversing valve energized in HEAT
TRANSFORMER
Reversing
Valve*
RCO
B
C
‡
JUMPER
WIRE
Compressor
Contactor
JUMPER
WIRE
* Reversing valve is energized when the
system switch is in the HEAT position
Fan
Relay
4
CONTINUED FROM SECOND PAGE
‡
NOTE
For 2-wire Heat only,
attach to RH and W
heat only, 3-wire, single transformer systems
‡
C
cool only, 3-wire, single transformer systems
YC
OB
G W
Fan
Relay
Heating
System
Figure 2. Typical wiring diagram for
Y
Cooling
System
G W
Fan
Relay
Figure 3. Typical wiring diagram for
JUMPER
RC
JUMPER
RCOB
WIRE
WIRE
24 VAC
THERMOSTAT
RH
SYSTEM
24 VAC
TRANSFORMER
THERMOSTAT
RH
SYSTEM
TRANSFORMER
Hot
120 VAC
Neutral
Hot
120 VAC
Neutral
RED jumper wire (provided with thermostat) must be
connected between thermostat RH and RC terminals
for proper thermostat operation with this system.
Y
OC‡B
Cooling
System
G W
Fan
Relay
Heating
System
Figure 4. Typical wiring diagram for
heat/cool, 4-wire, single transformer systems
NOTE
‡
The 24 Volt neutral connection to terminal C on the
thermostat is not required if the batteries are replaced
once a year with fresh “AA” Energizer® alkaline batteries.
JUMPER
WIRE
RH
RC
24 VAC
THERMOSTAT
SYSTEM
Hot
120 VAC
Neutral
TRANSFORMER
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Page 4
CHECK THERMOST A T OPERA TION
5
If at any time during testing your system does not operate
properly, contact a qualified service person.
Turn on power to the system.
Fan Operation
If your system does not have a G terminal connection, skip to
Heating System.
1. Move FAN switch to ON position. The blower should begin
to operate.
2. Move FAN switch to AUTO position. The blower should
stop immediately.
Heating System
1. Move SYSTEM switch to HEAT position. If the heating system
has a standing pilot, be sure to light it.
2. Press
ture. The heating system should begin to operate.
3. Press
ture. The heating system should stop operating.
to adjust thermostat setting above room tempera-
to adjust temperature setting below room tempera-
Cooling System
CAUTION
!
To prevent compressor and/or property damage, if the
outdoor temperature is below 50°F, DO NOT operate the
cooling system.
1. Move SYSTEM switch to COOL position.
2. Press
ture. The blower should come on immediately on high speed,
followed by cold air circulation
3. Press
ture. The cooling system should stop operating.
Before you begin programming your thermostat, you should be
familiar with its features and with the display and the location and
operation of the thermostat buttons. Your thermostat consists of
two parts: the thermostat cover and the base. To remove the
cover, pull it straight out from the base. To replace the cover, line
up the cover with the base and press until the cover snaps onto
the base.
to adjust thermostat setting below room tempera-
to adjust temperature setting above room tempera-
The Thermostat Buttons and Switches
1
Raises temperature setting.
Lowers temperature setting.
2
TIME button.
3
PRGM (program) button.
4
5
RUN (run program) button.
6
HOLD temperature button.
7
FAN switch (ON, AUTO).
SYSTEM switch (COOL, OFF, HEAT).
8
The Display
9
Indicates day of the week.
Flame icon ( ) is displayed when the SYSTEM switch is in
10
the HEAT position. Snowflake icon (
flashing) when the SYSTEM switch is in the COOL position.
Snowflake is displayed (flashing) if the thermostat is in
lockout mode to prevent the compressor from cycling too
quickly.
11
Displays “BATT” when the 2 “AA” batteries are low and
should be replaced. Only “BATT” with “LO” in the minutes
field are displayed when batteries are low with no system
power.
Alternately displays current time and temperature. Displays
12
“LO” in the minutes field when batteries are low.
13
The word “HOLD” is displayed when the thermostat is in the
HOLD mode. “HOLD” is displayed flashing when the thermostat is in a temporary HOLD Mode.
14
Displays currently programmed set temperature (this is blank
when SYSTEM switch is in the OFF position).
15
Displays FLTR when the system has run for the programmed
filter time period as a reminder to change or clean your air
filter.
)is displayed (non-
CONFIGURATION MENU
The configuration menu allows you to set certain thermostat
operating characteristics to your system or personal requirements.
Press RUN to make sure the thermostat is in the run program
mode, then press PRGM and RUN at the same time to enter the
configuration menu. The display will show the first item in the
configuration menu.
The configuration menu table summarizes the configuration
options. An explanation of each option follows.
Press HOLD to change to the next menu item or press TIME to go
backwards to the previous item in the menu. To exit the menu and
return to the program operation, press RUN. If no keys are
pressed within fifteen minutes, the thermostat will revert to normal
operation.
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Page 5
CHECK THERMOST A T OPERA TION
5
CONTINUED FROM FOURTH PAGE
1) Select Temporary Hold Time - The thermostat can hold any
temperature you set it to for the amount of time you select on
this option. Your choices are 0:00 to 8:00 hours in 15 minute
increments. 0:00 disables the function
Example:
1. You have selected 3:00 hours for the Temporary Hold time
period.
2. With the thermostat set to HEAT or COOL, press HOLD
for approximately five seconds until “HOLD” time (3:00
indicating 3 hours) appears as a setting reminder.
3. After releasing the button, “HOLD” on the display will blink.
4. Use
The thermostat will maintain this temperature setting for 3
hours with “HOLD” blinking to remind you it is in Temporary Hold. After 3 hours the thermostat will go back to the
program temperature and “HOLD” will no longer blink or
display.
2) Select FA or SL (Fast or Slow) Heating Cycle Rate - The
FA setting is frequently used for gas, oil or electric heat. The
SL setting produces a longer heating cycle which is normally
for hot water or steam (hydronic) systems. Both settings
produce very accurate temperature control and can be set to
your personal preference. FA cycles the system just under
1°F and the SL setting cycles at approximately 1.5°F.
3) Select backlit display - The display backlight improves
display contrast in low lighting conditions. Selecting backlight
ON will keep the light on for a short period of time after any
key is pressed. Selecting OFF will keep the light off.
4) Select Energy Management Recovery OFF or ON - Energy
Management Recovery (EMR) causes the thermostat to start
heating or cooling early to make the building temperature
reach the program setpoint at the time you specify. Heating
will start 5 minutes early for every 1° of temperature required
to reach setpoint.
Example: You select EMR and have your heating programmed to 65° at night and 70° at 7 AM. If the building
temperature is 65° the difference between 65° and 70° is 5°.
Allowing 5 minutes per degree the thermostat setpoint will
change to 70° at 6:35 AM. Cooling allows more time per
degree because it takes longer to reach temperature.
or to set the temperature to your preference.
5) Select filter replacement run time - The thermostat will
display “FLTR” after a set time of operation. This is a
reminder to change or clean your air filter. This time can be
set from 0 to 1950 hours in 50 hour increments. A selection
of 000 will cancel this feature. When “FLTR” is displayed,
you can clear it by pressing HOLD and RUN at the same time.
This resets the timer and starts counting the hours until the
next filter change. Changing the time in the menu also resets
the timer.
6) Select Compressor Lockout LOC OFF or ON - Selecting
LOC ON will cause the thermostat to wait 5 minutes before
turning on the compressor if the heating and cooling system
loses power. It will also wait 5 minutes minimum between
cooling cycles. This is intended to help protect the compressor from short cycling. Some newer compressors already
have a time delay built in and do not require this feature. Your
compressor manufacturer can tell you if the feature is already
present in their system. When the compressor time delay
occurs it will flash the (snowflake icon) for about five minutes
then turn on the compressor.
7) Select Temperature Display Adjustment 4 LO to 4 HI Allows you to adjust the room temperature display 4° higher
or lower. Your thermostat was accurately calibrated at the
factory but you have the option to change the display temperature to match your previous thermostat.
8) Select F° or C° Readout - Changes the display readout to
Centigrade or Fahrenheit as required.
OPERATING FEATURES
Now that you are familiar with the thermostat buttons and display,
read the following information to learn about the many features of
the thermostat.
• SIMULTANEOUS HEATING/COOLING PROGRAM STORAGE — When programming, you can enter both your heating
and cooling programs at the same time. There is no need to
reprogram the thermostat at the beginning of each season.
• TEMPERATURE OVERRIDE — Press
display shows the temperature you want. The thermostat will
override current programming and keep the room temperature at the selected temperature until the next program period
begins. Then the thermostat will automatically revert to the
program.
or until the
Configuration Menu
Step
* Press
Press Button(s)
1
2
3
4
5
6
7
8
9
HOLD to advance to next item or TIME to move backwards to previous item
PRGM and RUN
HOLD*
HOLD*
HOLD*
HOLD*
HOLD*
HOLD*
HOLD*
RUN
Displayed
(Factory Default)
HOLD (0:00)
(FA)
d-L (ON)
E (ON)
Filter (000)
LOC (OFF)
0 HI (0)
(F)
Press or to select:
0 to 8 hrs (in 15 minute increments)
0 to 1950 hours (in 50 hour increments)
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SL
OFF
OFF
ON
4 LO to 4 HI
C
Comments
Select temporary Hold time
Select FA or SL (Fast or Slow) heating cycle rate
Select display backlight OFF or ON
Select Energy Management Recovery OFF or ON
Select filter replacement run time
Select compressor lockout OFF or ON
Select temperature display adjustment higher or lower
Select temperature display to F or C
Returns to normal operation
Page 6
CHECK THERMOST A T OPERA TION
5
CONTINUED FROM FIFTH PAGE
Set Current Time and Day
1. Press TIME button once. The display will show the hour only.
• HOLD TEMPERATURE — The thermostat can hold any
temperature within its range for an indefinite period without
reverting to the programmed temperature. Momentarily press
HOLD button. HOLD will be displayed. Then choose the
desired temperature by pressing
or . The thermostat
will hold the room temperature at the selected setting until
you press RUN button to start program operation again.
• CONFIGURATION MENU — Allows you to customize certain thermostat options.
PROGRAMMING Y OUR THERMOST A T
6
This section will help you plan your thermostat’s program to meet
your needs. For maximum comfort and efficiency, keep the
following guidelines in mind when planning your program.
• When heating (cooling) your building, program the temperatures to be cooler (warmer) when the building is vacant or
during periods of low activity.
• During early morning hours, the need for cooling is usually
minimal.
Look at the factory preprogrammed times and temperatures shown
below. If this program will suit your needs, simply press the RUN
button to begin running the factory preset program.
If you want to change the preprogrammed times and temperatures, follow these steps.
Determine the time periods and temperatures for your weekday
and weekend programs. You must program four periods for both
the weekday and weekend program. However, you may use the
same heating and cooling temperatures for consecutive time
periods. You can choose start times, heating temperatures, and
cooling temperatures independently for both weekday and weekend programs (for example, you may select 5:00 AM and 70° as
the weekday 1st period heating start time and temperature, and
also choose 7:00 AM and 76° as the weekday 1st period cooling
start time and temperature). Use the table at the bottom of the
page to plan your program time periods and the temperatures you
want during each period. You may also want to look at the sample
program table to get an idea of how the thermostat can be
programmed.
Entering Your Program
Follow these steps to enter the heating and cooling programs you
have selected.
EXAMPLE:
PM
2. Press and hold either or until you reach the correct
hour and AM/PM designation (AM begins at midnight; PM
begins at noon).
3. Press TIME once. The display window will show the minutes
only.
EXAMPLE:
4. Press and hold either or until you reach the correct
minutes.
5. Press TIME once. The display will show the day of the week.
6. Press or until you reach the current day of the week.
7. Press RUN once. The display will show the correct time and
room temperature alternately.
Enter Heating Program
1. Move the SYSTEM switch to HEAT.
2. Press PRGM once. “MO TU WE TH FR” (indicating weekday
program) will appear in the display. Also displayed are the
currently programmed start time for the 1st heating period and
the currently programmed temperature (flashing).
MO TU WE TH FR
EXAMPLE:
This display window shows that for the 1st weekday period,
the start time is 6:00 AM, and 70° is the programmed temperature (this example reflects factory preprogramming).
3. Press or to change the displayed temperature to your
selected temperature for the 1st heating program period.
4. Press TIME once (the programmed time will flash). Press
or until your selected time appears. The time will change
in 15 minute increments. When your selected time is displayed, press TIME again to return to the change temperature
mode.
5. Press PRGM once. The currently programmed start time and
setpoint temperature for the 2nd heating program period will
appear.
6. Repeat steps 3 through 5 to select the start time and heating
temperature for the 2nd heating program period.
AM
Heating/Cooling Schedule Plan (Factory Program)
WEEKDAY (5 DAY)
Period
1ST 6:00 AM 70˚F 6:00 AM 70˚F 6:00 AM 70˚F
2ND 8:00 AM 62˚F 8:00 AM 62˚F 8:00 AM 62˚F
3RD 5:00 PM 70˚F 5:00 PM 70˚F 5:00 PM 70˚F
4TH 10:00 PM 62˚F 10:00 PM 62˚F 10:00 PM 62˚F
1ST 6:00 AM 78˚F 6:00 AM 78˚F 6:00 AM 78˚F
2ND 8:00 AM 85˚F 8:00 AM 85˚F 8:00 AM 85˚F
COOL HEAT
3RD 5:00 PM 78˚F 5:00 PM 78˚F 5:00 PM 78˚F
4TH 10:00 PM 82˚F 10:00 PM 82˚F 10:00 PM 82˚F
Start
Time Temperature
SAMPLE
SATURDAY (1 DAY)
Start
Time Temperature
SUNDAY (1 DAY)
Start
Time Temperature
Period
1ST
2ND
3RD
4TH
1ST
2ND
COOL HEAT
3RD
4TH
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Heating/Cooling Schedule Plan (Factory Program)
WEEKDAY (5 DAY)
Start
Time Temperature
SAMPLE
SATURDAY (1 DAY)
Start
Time Temperature
SUNDAY (1 DAY)
Start
Time Temperature
Page 7
PROGRAMMING Y OUR THERMOST A T
6
CONTINUED FROM SIXTH PAGE
1. Move SYSTEM switch to COOL position.
2. Follow the procedure for entering your heating program, using
your selected cooling times and temperatures.
7. Repeat steps 3 through 5 for the 3rd and 4th heating program
periods. Weekday heating programs are now complete.
8. Press PRGM once. “SA” will appear in the display, along with
the start time for the 1st heating period and the currently
programmed temperature for Saturday.
9. Repeat steps 3 through 7 to complete Saturday heating
programming.
10.Press PRGM once. “SU” will appear on the display along with
start time and currently programmed temperature for the 1st
heating period for Sunday. Repeat steps 3 through 7 to
complete Sunday heating programming.
11. When you have completed entering your heating program,
press RUN.
Enter Cooling Program
If the outside temperature is below 50°F, disconnect
power to the cooling system before programming. Energizing the air conditioner compressor during cold
weather may cause personal injury or property damage.
SPECIFICATIONS
7
ELECTRICAL DATA
Electrical Rating:
0 to 30 VAC 50/60 Hz. or D.C.
0.05 to 1.2 Amps (Load per terminal)
1.5 Amps Maximum Total Load (All terminals combined)
Check Your Programming
Follow these steps to check your thermostat programming one
final time before beginning thermostat operation.
1. Move SYSTEM switch to HEAT position.
2. Press PRGM to view the 1st weekday heating period time and
temperature. Each time you press PRGM, the next heating
period time and temperature will be displayed in sequence for
weekday, then weekend program periods (you may change
any time or temperature during this procedure).
3. Press RUN.
4. Move SYSTEM switch to COOL position.
5. Repeat step 2 to check cooling temperatures.
6. Press RUN to begin program operation.
YOUR THERMOSTAT IS NOW COMPLETELY PROGRAMMED
AND READY TO AUTOMATICALLY PROVIDE MAXIMUM COMFORT AND EFFICIENCY!
THERMAL DATA
Setpoint Temperature Range:
45°F to 90°F (7°C to 32°C)
Operating Ambient Temperature Range:
32°F to 105°F
Operating Humidity Range:
0 to 90% RH (non-condensing)
Shipping Temperature Range:
-40°F to 150°F
TROUBLESHOOTING
8
Reset Operation
If a voltage spike or static discharge blanks out the display or
causes erratic thermostat operation you can reset the thermostat
by pressing
thermostat to the factory defaults. If the thermostat has power,
, and TIME at the same time. This resets the
has been reset and still does not function correctly contact your
heating/cooling service person or place of purchase.
Batteries
For optimum performance, we recommend replacing batteries
once a year with fresh “AA” Energizer
®
alkaline batteries.
Symptom Possible Cause Corrective Action
No Heat/No Cool/No Fan 1. Blown fuse or tripped circuit breaker. Replace fuse or reset breaker.
(common problems) 2. Furnace power switch to OFF. Turn switch to ON.
3. Furnace blower compartment door or Replace door panel in proper position to engage
panel loose or not properly installed. safety interlock or door switch.
No Heat 1. Pilot light not lit. Re-light pilot.
2. SYSTEM Switch not set to HEAT. Set SYSTEM Switch to HEA T and raise temper ature
above room temperature.
3. Loose connection to thermostat or system. Verify thermostat and system wires are securely
attached.
4. Furnace Lock-Out Condition. Heat may also Many furnaces have safety devices that shut
be intermittent. down when a lock-out condition occurs. If the
heat works intermittently contact the furnace
manufacturer or local service person for
assistance.
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Page 8
TROUBLESHOOTING
8
CONTINUED FROM SEVENTH PAGE
Symptom Possible Cause Corrective Action
No Heat (continued) 5. Heating system requires service or Diagonistic: Set SYSTEM Switch to HEAT and
thermostat requires replacement. raise the setpoint above room temperature. Within
a few seconds the thermostat should make a soft
click sound. This sound usually indicates the
thermostat is operating properly. If the thermostat
does not click, try the reset operation listed below .
If the thermostat does not click after being reset
contact your heating and cooling service person
or place of purchase for a replacement. If the
thermostat clicks, contact the furnace manufacturer
or a service person to verify the heating is operating
correctly.
No Cool 1. SYSTEM Switch not set to COOL. Set SYSTEM Switch to COOL and lower temperature
below room temperature.
2. Loose connection to thermostat or system. Verify thermostat and system wires are securely
attached.
3. Cooling system requires service or Same procedure as diagnostic for No Heat
thermostat requires replacement. condition except set the thermostat to COOL and
lower the setpoint below the room temperature.
There may be up to a five minute delay before the
thermostat clicks in Cooling.
Heat, Cool or Fan Runs Constantly. 1. FAN Switch set to Fan ON. Check each wire connection to verify they are not
2. Possible short in wiring. shorted or touching together. No bare wire should
3. Possible short in thermostat. stick out from under terminal screws. Try resetting
4. Possible short in heat/cool/fan system. the thermostat as described below. If the condition
persists the manufacturer of your system or
service person can instruct you on how to test the
Heat/Cool system for correct operation. If the
system operates correctly, replace the thermostat.
Furnace Cycles Too Fast or Too Slow 1. The location of the thermostat and/or the Digital thermostats normally provide precise
(narrow or wide temperature swing) size of the Heating System may be temperature control and may cycle faster than
influencing the cycle rate. some older mechanical models. A faster cycle
rate means the unit turns on and off more
frequently but runs for a shorter time so there is
no increase in energy use. If you would like to
increase the cycle time, clip Jumper W-905 as
mentioned in the instructions for Hydronic Heating
Systems. It is not possible to shorten the cycle
time. If an acceptable cycle rate is not achieved as
received or by clipping W-905 contact a local
service person for additional suggestions.
Cooling Cycles Too Fast or Too Slow 1. The location of the thermostat and the size The cycle rate for cooling is fixed and can not be
(narrow or wide temperature swing) of the Cooling System can influence the adjusted. Contact a local service person for
cycle rate. suggestions.
Thermostat Setting and Thermostat 1. Thermostat thermometer setting requires The thermometer can be adjusted +/- 3 degrees.
Thermometer Disagree adjustment. See Temperature Display Adjustment in the
Operation section.
Thermostat Does Not Follow Program 1. AM or PM set incorrectly in program. Check current clock and program settings
2. AM or PM set incorrectly on the clock. including the AM or PM designations for each
3. Voltage spike or static discharge. time period. If a voltage spike or a static discharge
occurs use the Reset Operation listed below.
Blank Display and/or Keypad 1.Voltage spike or static discharge. Replace batteries and check heat/cool system
Not Responding 2. Battery change required. for proper operation. If a voltage spike occurs use
the Reset Operation listed below.
The Emerson logo is a
trademark and a service mark
of Emerson Electric Co.
www.white-rodgers.com
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