1F88-270 Thr

hruu -279
Heating & Air Conditioning
5-1-1 Programmable/Non-programmable, Auto
Changeover, Multi-Stage/Heat Pump Thermostat
INSTALLATION INSTRUCTIONS

Operator: Save these instructions for future use!

FAILURE TO READ AND FOLLOW ALL INSTRUCTIONS CAREFULLY BEFORE
INSTALLING OR OPERATING THIS CONTROL COULD CAUSE PERSONAL
INJURY AND/OR PROPERTY DAMAGE.
PREPARATIONS
YOUR THERMOSTAT REPLACES
Assemble tools required as shown below.
Description 1F88
Heat Pump (No Aux. or Emergency Heat) Yes
Heat Pump (with Aux. or Emergency Heat) Yes
Standard Heat & Cooling Systems Yes FLAT BLADE SCREWDRIVER
WIRE CUTTER/STRIPPER
Two Stage Heat & Two Stage Cool Yes
Standard Heat Only Systems Yes HAND OR POWER
DRILL WITH 3/16 INCH
Millivolt Heat Only Systems – Floor or Wall Furnaces Yes DRILL BIT, IF NEEDED

Standard Central Air Conditioning Yes

SPIRIT LEVEL OR PLUMB BOB AND LINE OPTIONAL—
Gas or Oil Heat Yes THERMOSTAT DOES NOT NEED TO BE LEVEL TO WORK PROPERLY

Electric Furnace Yes

Hydronic (Hot Water) Zone Heat – 2 Wires Yes
Hydronic (Hot Water) Zone Heat – 3 Wires No
REMOVING OLD THERMOSTAT
! CAUTION
To prevent electrical shock and/or equipment dam-
age, disconnect electric power to system at main fuse ELEC/GAS SWITCH

or circuit breaker box until installation is complete.

Before removing wires from old thermostat's switching sub- RC/PS

SWITCH
base, label each wire with the terminal designation.
1. Shut off electricity at the main fuse box until installation is
MOUNTING MOUNTING
complete. Ensure that electrical power is disconnected. HOLE HOLE
CM/NO CM
2. Remove Old Thermostat
Thermostat: A standard heat/cool SWITCH

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 Figure 1 – Thermostat base
captive screws.
c. The switching subbase, which is removed by
unscrewing the mounting screws that hold it on
the wall or adaptor plate. ATTENTION! This product does not contain mercury. How-
ever, this product may replace a unit which contains mercury.
3. Remove the front cover of the old thermostat. With
wires still attached
attached, remove wall plate from the wall. If Do not open mercury cells. If a cell becomes damaged, do not
the old thermostat has a wall mounting plate, remove the touch any spilled mercury. Wearing non-absorbent gloves,
thermostat and the wall mounting plate as an assembly. clean up the spilled mercury and place into a container which
can be sealed. If a cell becomes damaged, the unit should be
4. Identify each wire attached to the old thermostat. discarded.
5. Disconnect the wires from the old thermostat one at a Mercury must not be discarded in household trash. When the
time. DO NOT LET WIRES FALL BACK INTO THE unit this product is replacing is to be discarded, place in a
WALL
WALL.
suitable container and return to White-Rodgers at 2895 Harrison
6. Install new thermostat using the following procedures. Street, Batesville, AR 72501 for proper disposal.

White-Rodgers is a division PART NO. 37-6588F

of Emerson Electric Co. Replaces 37-6588E
www.white-rodgers.com 0549

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 MOUNTING AND WIRING
! CAUTION
! WARNING Take care when securing and routing wires so they do
Do not use on circuits exceeding specified voltage. not short to adjacent terminals or rear of thermostat.
Higher voltage will damage control and could cause Personal injury and/or property damage may occur.
shock or fire hazard.
Attach Thermostat Base to Wall
Do not short out terminals on gas valve or primary 1. Remove the packing material from the thermostat. Gently
control to test. Short or incorrect wiring will damage pull the cover straight off the base. Forcing or prying on
thermostat and could cause personal injury and/or the thermostat will cause damage to the unit.
property damage.
2. Connect wires beneath terminal screws on base using
Thermostat installation and all components of the appropriate wiring schematic (see figs. 2 through 4).
system shall conform to Class II circuits per the NEC 3. Place base over hole in wall and mark mounting hole
code. locations on wall using base as a template.
4. Move base out of the way. Drill mounting holes.
Electric/Gas Switch (Fan Option)
5. Fasten base loosely to wall, as shown in fig. 1, using two
The ELEC/GAS switch is factory set to the ELEC position. In
mounting screws. Place a level against bottom of base,
this position, the thermostat will power the circulator fan on a
adjust until level, and then tighten screws. (Leveling is for
call for heat. Electric heat systems may require the switch to
appearance only and will not affect thermostat operation.)
be in the ELEC position.
If you are using existing mounting holes, or if holes drilled
If your system does not require that the thermostat power are too large and do not allow you to tighten base snugly,
the circulator fan, this switch should be set to the GAS use plastic screw anchors to secure subbase.
position. Typically, gas and oil heating systems do not
6. Push excess wire into wall and plug hole with a fire-
require the thermostat to power the circulator fan during a
resistant material (such as fiberglass insulation) to
call for heat. If your heat is gas or oil, the switch should be
prevent drafts from affecting thermostat operation.
set to the GAS position.
When the thermostat is configured for Heat Pump, the Battery Location
thermostat will always power the circulator fan on a call for 2 "AA" alkaline batteries are included in the thermostat at the
heat in the HEAT mode. The ELEC/GAS switch must be set factory with a battery tag to prevent power drainage. You
to match the type of Auxiliary heat your system uses for must remove the battery tag to engage the batteries.
proper operation in the EMERgency mode.
If BATT is displayed, the batteries are low and should be
RC/PS Switch (Thermostat Power Option) replaced with fresh "AA" alkaline batteries. To replace
batteries, set system to OFF, install the batteries along the
The RC/PS switch is factory set to the RC position. In this
top of the base (see Fig. 1). The batteries must be installed
position, the system must have enough wires to be powered
with the positive (+) end to the left.
from the 24 VAC transformer with the common wire. When
possible, the thermostat should be configured in this
manner.
If the system does not have enough wires to be powered
from the 24 VAC transformer, the thermostat can be config-
ured for power stealing. For power stealing, move the RC/PS
switch to the PS position.

NOTE
All wiring diagrams are for typical systems only. Refer to
If the RC/PS switch is set to PS, the C terminal (24 VAC equipment manufacturers' instructions for specific system wir-
Common) MUST NOT have a wire connected to it. ing information.

E/W1
THERMOSTAT
O B Y2 Y1 G W2 C L R
SYSTEM
SYSTEM
Reversing Valve Reversing Valve 2nd Stage MONITOR
Energized in Cool Energized in Heat, Compressor Fan Emergency SWITCH
Compressor Aux or 1st Aux.
Mode Off, Emergency Relay Relay
Contactor Stage
Mode (Stage 2) Relay Hot
24 VAC 120 VAC
Neutral
TRANSFORMER
(Class II Current Limited)
Figure 2. Typical wiring diagram for single transformer heat pump systems

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 WIRING DIAGRAMS
NOTE
If safety circuits are in only one of the systems, remove
the transformer of the system with NO safety circuits.

E/W1
THERMOSTAT
O B Y2 Y1 G W2 C L R
CUT AND SYSTEM
TAPE OFF! Reversing SYSTEM
Reversing 2nd Stage Fan MONITOR Limit or
Valve Safety
HOT Valve Compressor Relay Emergency SWITCH
Energized in or 1st Aux. Switches
Energized in
120 VAC 24 VAC Heat, Off, Aux Stage
Cool Mode Compressor
Emergency Relay Relay
NEUTRAL Contactor (Stage 2) Hot
Mode
24 VAC 120 VAC
Neutral
TWO COMMONS MUST
TRANSFORMER
BE JUMPERED TOGETHER!
(Class II Current Limited)
Figure 3. Typical wiring diagram for two transformer heat pump systems with NO safety circuits

NOTE
Polarity must be observed. If the HOT side of the second transformer
is jumpered to the COMMON side of the first transformer a short will
be made. Damage to equipment will occur when power is restored.

E/W1
THERMOSTAT
O B Y2 Y1 G W2 C L R
SYSTEM
Limit or
Limit or Safety HOT
Reversing Safety Switches
24 VAC 120 VAC
Emergency SYSTEM Switches
Reversing Valve 2nd Stage Fan or 1st Aux. NEUTRAL
MONITOR
Valve Energized in Compressor Relay Stage Relay SWITCH 24 VAC Auxiliary
Energized in Heat, Off, ACCESSORY Heating NOTE
Aux
Cool Mode Emergency Compressor RELAY N.O. Transformer The accessory relay scheme
Mode Relay CONTACT (Class II
Contactor is required when safety
(Stage 2) Current Limited)
circuits exist in both systems.
COMMON

TWO COMMONS MUST Limit or Limit or

BE JUMPERED TOGETHER! Safety Safety
Switches Switches HOT

COMMON 24 VAC 120 VAC

NEUTRAL
Heat Pump Transformer
(Class II Current Limited)

Figure 4. Typical wiring diagram for two transformer heat pump systems with safety circuits in BOTH systems

Heat Pump Terminal Outputs

Refer to equipment manufacturers' instructions for specific one transformer. If transformer safety circuits are in only one of
system wiring information. the systems, remove the transformer of the system with NO
You can configure the thermostat for use with the following safety circuits. If required, replace remaining transformer with
heat pump system types: a 75VA Class II transformer. After disconnecting one trans-
HEAT PUMP TYPE 1 1. Single stage compressor system; gas former, the two commons must be jumpered together.
or electric backup. Use the terminal output information below to help you wire the
This thermostat is designed to operate a single-transformer thermostat properly for your multi-stage system. After wiring,
system. If you have a two-transformer system, cut and tape off see CONFIGURATION section for proper thermostat configu-
ration.
THERMOSTAT TERMINALS (HEAT PUMP)
SYSTEM L C R W2 E/W1 Y2 Y1 G O B
Heat Malfunction 24 Volt 24 Volt Heat Mode Heat mode No Heat and Blower/Fan Energized Energized Energized
Pump 1 Light (Common) (Hot) 3rd stage 2nd stage Output Cool mode on call for Heat in Cool in Heat
Set RC/PS Emergency or 1st stage and Cool Mode OFF
Heat switch to mode Emergency 2nd (compressor) Set GAS/ELEC switch Emergency
Pump 2 RC 2nd stage Mode stage for Emergency mode mode
1st stage compressor

E/W1
THERMOSTAT
O B Y1 Y2 G W2 C R
SYSTEM
Compressor Heat
Contactor Relay
Reversing Reversing
Stage 2 Stage 1 Hot
Valve Valve
Energized in Energized in 24 VAC 120 VAC
Cool Mode Heat Mode Compressor Heat
Fan Neutral
Off Emergency Contactor Relay
Relay TRANSFORMER
Stage 1 Stage 2 (Class II, Current Limited)

Figure 5. Typical wiring diagram for single transformer multi-stage systems

3
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 Multi-Stage Terminal Outputs
Refer to equipment manufacturers' instructions for specific one transformer. If transformer safety circuits are in only one of
system wiring information. the systems, remove the transformer of the system with NO
You can configure the thermostat for use with either multi-stage safety circuits. If required, replace remaining transformer with
electric heat systems or multi-stage gas systems. When con- a 75VA Class II transformer. After disconnecting one trans-
figured for electric heat, the G terminal (blower/fan) will be former, the two commons must be jumpered together.
energized on a call for heat. Use the terminal output information below to help you wire the
This thermostat is designed to operate a single-transformer thermostat properly for your multi-stage system. After wiring,
system. If you have a two-transformer system, cut and tape off see CONFIGURATION section for proper thermostat configu-
ration.

THERMOSTAT TERMINALS (MULTI-STAGE)

SYSTEM L C R W2 /W1
E/W1 Y2 Y1 G O B
Multi-stage Malfunction 24 Volt 24 Volt Heat Mode Heat mode Cool Mode Cool Mode Blower/Fan Energized Energized Energized
Light (Common) (Hot) 2nd stage 1st stage 2nd stage 1st stage on call for Cool (and in Cool in Heat, Off,
Set RC/PS Heat if configured Mode Emergency
switch to RC to Electric Heat) Modes

CHECK THERMOSTAT OPERATION

NOTE Emergency System
To prevent static discharge problems, touch side of EMER bypasses the Heat Pump to use the heat source
thermostat to release static build-up before touching wired to terminal E on the thermostat. EMER is typically
any keys. used when compressor operation is not desired, or you
prefer back-up heat only.
If at any time during testing your system does not operate 1. Press SYSTEM button to select EMER EMER
EMER. "EMER
EMER" will flash
properly, contact a qualified serviceperson. on the display.
Fan Operation 2. Press to adjust thermostat setting above room
temperature. The Aux. heating system will begin to
If your system does not have a G terminal connection, skip to STG1
operate. The display will show "STG1 EMER
STG1" flashing "EMER
EMER"
Heating System
System. HEAT
and "HEAT
HEAT" to indicate that the Aux. system is
1. Turn on power to system. operating.
2. Move FAN switch to ON position. The blower should 3. Press to adjust the thermostat below room tempera-
begin to operate. ture. The Aux. heating system should stop operating.
3. Move FAN switch to AUTO position. The blower should
stop immediately.

! CAUTION ! CAUTION
Do not allow the compressor to run unless the com- To prevent compressor and/or property damage, if
pressor oil heaters have been operational for 6 hours the outdoor temperature is below 50°F, DO NOT
and the system has not been operational for at least operate the cooling system.
5 minutes.
Cooling System
Heating System 1. Press SYSTEM button to select COOLCOOL.
1. Press SYSTEM button to select HEATHEAT. If the auxiliary 2. Press to adjust thermostat setting below room
heating system has a standing pilot, be sure to light it. temperature. The blower should come on immediately on
2. Press to adjust thermostat setting to 1° above room high speed, followed by cold air circulation. The display
temperature. The heating system should begin to STG1
should show "STG1
STG1". If the setpoint temperature display
operate. The display should show "STG1STG1
STG1". However, if is flashing, the compressor lockout feature is operating
the system configuration is set to HP1 or HP2 and set- (see Configuration menu, item 5).
point temperature display is flashing, the compressor 3. Adjust temperature setting to 3° below room temperature.
lockout feature is operating (see Configuration menu, The second stage cooling should begin to operate and
item 5). the display should show “STGSTG 1+2
1+2”.
3. Adjust temperature setting to 3° above room temperature. 4. Press to adjust the temperature setting above room
If your system configuration is set at MS2, HP2 or HP1, temperature. The cooling system should stop operating.
the auxiliary heat system should begin to operate and
the display should show “STGSTG 1+2
1+2”.
4. Press to adjust the thermostat below room tempera-
ture. The heating system should stop operating.

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 OPERATION
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 21
cover snaps onto the base.

NOTE
Some of the features and/or displays of this thermo-
stat may not be used by the utility.

The Thermostat Buttons and Switches

1 Raises temperature setting

2 Lowers temperature setting.

9
3 TIME button. 16
4 PRGM (program) button.
12 13
5 RUN (run program) button.

6 HOLD temperature button.

18
7 ON
ON, AUTO
FAN switch (ON AUTO) 14 10 17

8 COOL
COOL, AUTO
SYSTEM button (COOL AUTO, HEAT
HEAT, EMER
EMER, OFF
OFF)
20
21 Lights to indicate a curtailment event is occurring or will 15
be occurring soon.
12
The Display L M H CRITICAL
9 Indicates day of the week.

10 HEAT" is displayed when the system is in HEAT

"HEAT
HEAT 19 11
COOL
mode. "COOL
COOL" is displayed when the system is in
Figure 6 – Thermostat display, buttons and switches
COOL mode. "HEATHEAT COOL
HEAT" and "COOL
COOL" are displayed
simultaneously when thermostat is in AUTO mode.
HOLD
The word "HOLD
HOLD" is displayed when the thermostat is
in the HOLD mode. "HOLD
HOLD
HOLD" is displayed flashing 17 Stage1 & 2 indicators: The thermostat shall indicate
when the thermostat is in a temporary HOLD mode mode. when the first and second stage is energized except
FLTR
Displays "FLTR
FLTR" when the system has run for the in emergency mode. The icon is STG 1 for the first
programmed filter time period as a reminder to change stage energized. The icons for the first and second
or clean your filter. stage energized are STG1+2 located in the upper
EMER
"EMER
EMER" is displayed flashing when the system is in right side of the display.
EMER mode. 18 Displays flashing to indicate that an event modification
11 BATT
Displays "BATT
BATT" when the 2 "AA" batteries are low has been received and completed. Will continue to
BATT
and should be replaced. Only "BATT
BATT" and "LO LO
LO" in the flash until any key is pressed.
minutes field are displayed when batteries are low with 19 Indicates the current curtailment level of the system.
no system power. The system can be in Low (L), Medium (M), High (H),
12 Alternately displays current time and temperature. Dis- or Critical (CRITICAL) peak load curtailment condition.
LO
plays "LO
LO" in the minutes field when batteries are low. 20 Will display "SAVE
SAVE" during curtailment, or other
SAVE
13 Displays currently programmed set temperature (this messages.
is blank when SYSTEM is OFF
OFF).
14 Display ( ) when in keypad lockout mode.

15 Indicates a fault in the heating/cooling system. It does

not indicate a fault in the thermostat.

16 Display ( ) when limited range is activated.

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 CONFIGURATION MENU
Press the System button until OFF is displayed, then press the and simultaneously

INSTALLER/CONFIGURATION MENU
Press Displayed Press or
Step Button(s) (Factory Default) to select Comments

1 System MS2 SS1, HP2, HP1 Selects Single stage, Multi-stage, or Heat Pump
(Single stage or 2-stage) System Configuration
2 System PRG 4 PRG 0, PRG 2 Selects Programmable Periods
3 System EMR OFF Selects Energy Management Recovery OFF or ON
(ON)
4 System FA SL Selects Fast or Slow Cycle Selection
5 System CL CL Selects Compressor Lockout CL OFF or ON
(OFF) (ON)
6 System CDL CDL Selects Backlight Display
(ON) (OFF)
7 System FA FA Selects Fast Second Stage ON or OFF
(ON) (OFF)
8 System 0 FLTR 0 -1950 (increments of 50) Selects filter replacement run time. 0 = Disabled
9 System 0°F 4 LO to 4 HI Selects Temperature Display Adjustment 4 LO to 4 HI
(Room Temperature)
10 System 4:00 HOLD 0:00 to 8:00 Selects Temporary Program Override Time
(increments of 15 minutes) 0:00 = Disabled
11 System °F °C For °C selection
12 System LR LR 62 to LR89 Selects Limited HEAT range
(90)
13 System LR LR 46 to LR 82 Selects Limited COOL range
(45)
14 System Comp Run Time Press and to reset to 0 Shows run time of compressor
15 System O/S day (SASU) Show offset weekend days Shows two days of week for two day program
16 System (OFF) (ON) Selects Keypad Lockout
17 0 001 to 999 Selects Keypad lockout combination number
Press System to set code
Run Returns to the OFF position

The configuration menu allows you to set certain thermostat mable, SYSTEM key selection will skip EMR (item 3) and
operating characteristics to your system or personal require- temporary program override (item 10).
ments. 3) Select Energy Management Recovery OFF or ON –
Set SYSTEM button to OFF OFF, then simultaneously press Energy Management Recovery (EMR) causes the
and to enter configuration menu. The display will thermostat to start heating or cooling early to make the
show the first item in the configuration menu. building temperature reach the program setpoint at the
time you specify. Heating will start 5 minutes early for
The configuration menu table summarizes the configuration
every 1° of temperature required to reach setpoint.
options. An explanation of each option follows.
Example: You select EMR and have your heating program-
Press SYSTEM to change to the next menu item. To exit the
med to 65° at night and 70° at 7 AM. If the building temp-
menu and return to the program operation, press RUN. If no
erature is 65° the difference between 65° and 70° is 5°.
keys are pressed within fifteen minutes, the thermostat will Allowing 5 minutes per degree the thermostat setpoint will
revert to normal operation. change to 70° at 6:35 AM. Cooling allows more time per
1) Single Stage, Multi-stage or Heat Pump System degree because it takes longer to reach temperature.
Configuration – This control can be configured for Heat 4) Fast or Slow Cycle Selection – The factory default setting
Pump or two stage heat/two stage cool multi-stage is fast cycle, which cycles 1st stage at approximately 1.2°F
MS2
operation. The display indicates "MS2
MS2" (default for multi- and 2nd stage 0.75°F. If you prefer slow cycle, press the
stage mode) in the display. The Multi-stage configuration temperature key to change to SL. The 1st stage and 2nd
can be toggled to SS1
SS1, HP2
HP2, or HP1 by pressing the stage would be 1.5°F and 1.2°F respectively.
or key. In Multi-stage configuration, system button will
not have EMER
EMERgency mode. 5) Select Compressor Lockout CL OFF or ON – Selecting
CL ON will cause the thermostat to wait 5 minutes before
2) Programmable Periods – This control can be config- turning on the compressor if the heating and cooling system
ured for 4, 2 or 0 programmable periods. The display loses power. It will also wait 5 minutes minimum between
PRG 4
indicates "PRG 4" in the display as default. The program- cooling and heating cycles. This is intended to help protect
mable periods can be toggled to 2 or 0 by pressing the the compressor from short cycling. Some newer compres-
or PRG 0
keys. With "PRG 0" selected for non-program- sors already have a time delay built in and do not require

6
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 CONFIGURATION MENU
this feature. Your compressor manufacturer can tell you if Limited Cool Range – This feature provides a minimum
13)Limited
the lockout feature is already present in their system. When setpoint temperature for cool. The default setting is 45°F. It
the thermostat compressor time delay occurs it will flash the can be changed between 46°F and 82°F by pressing the
setpoint for about five minutes. or key.
6) Select Backlight Display – The display backlight improves Compressor Run Time – The total run time in hours of
14)Compressor
display contrast in low lighting conditions. When the "C" compressor stage (Y) are displayed in the menu mode. This
terminal is powered, selecting backlight CdL ON will keep COMP RUN TIME
menu selection will display the words "COMP TIME" in
the light on continuously. Select backlight OFF will keep the alpha display one second for each word along with the
the light on momentarily after any key is pressed. When the 0 to 1999
total run time (0 1999) below the alpha display and the
"C" terminal is not powered, the light will be on momentarily word HR
HR. Pressing the or keys at the same time, when
after any key is pressed no matter the backlight is selected compressor run time is displayed, will clear the run time for
ON or OFF. the compressor. This feature may be exited by pressing the
RUN key or when 120 seconds has elapsed without
7) Select (Fast) Second Stage ON or OFF – In the run mode,
keypad activity. The run times are copied from RAM into
if the setpoint temperature is manually raised by 3°F (2°C)
EEPROM every 24 hours.
or more above the actual temperature with the , and the
fast second stage feature is enabled, FA ON, the second Offset Week End Day – The thermostat may operate at a
15)Offset
stage will energize immediately. With FA OFF, second different day offset to allow the weekend day programs to
stage will not energize until the setpoint temperature is 1°F represent other consecutive days during the week. This
or more above actual temperature for more than ten min- menu selection will display the words O/S in the alpha
utes. display and DAY below the alpha display. Also, the current
offset weekend days will be displayed in the day area.
8) Select filter replacement run time – The thermostat will
FLTR Pressing the key will increment the consecutive two days
display "FLTR
FLTR" after a set time of operation. This is a remind-
and the key will decrement. This feature may be exited
er to change or clean your air filter. This time can be set from
by pressing the RUN PRGM key or when 120 seconds has
0 to 1950 hours in 50 hour increments. A selection of 000
will cancel this feature FLTR elapsed without keypad activity. The offset weekend days
feature. When "FLTR FLTR" is displayed, you
are copied from RAM into EEPROM every 24 hours.
can clear it by pressing HOLD and RUN at the same time.
This resets the timer and starts counting the hours until the 16 & 17) Keypad Lockout – This menu selection will display
next filter change. Contact your system manufacturer for a lock ( ) icon. The and are used to toggle the function
specific replacement/maintenance interval. and display the lock icon and OFF (keypad not locked out,
9) Select Temperature Display Adjustment 4 LO to 4 HI – default) indicating in the time digits to the lock icon and ON
Allows you to adjust the room temperature display up to 4° (keypad locked out). When the keypad lockout function is
higher or lower. Your thermostat was accurately calibrated enabled (ONON
ON), and the SYSTEM key is pressed again, the
at the factory but you have the option to change the display display will indicate the number 0 (default, still disabled) in
temperature to match your previous thermostat. The cur- the time digits. The and are used to set the combina-
rent or adjusted room temperature will be displayed on the tion number from 0 to 999 0 " will not be a valid combination.
999. "0
left side of the display. If a combination of 0 is selected and the SYSTEM key is
pressed the menu will be exited and keypad lockout will not
Select Temporary Program Override Time – The thermo-
10)Select be evoked. If 1 to 999 is selected and the SYSTEM key is
stat can hold any temperature you set it to for the amount pressed again, the combination is locked into non-volatile
of time you select on this option. Your choices are 0:00 to memory and the menu is exited. The lock icon (to designate
8:00 hours in 15 minute increments. 0:00 means disable. keypad locked with a valid combination) will display when
Example: the menu is exited. The SYSTEM key will operate for 10
seconds after the menu mode is exited to allow the user to
1. You have selected 3:00 hours for the Temporary Pro- change the mode from OFF to the desired system mode.
gram Override time period.
While the keypad is locked out, a simultaneous press of
2. With the thermostat set to Heat or Cool, press HOLD and will enter the menu item from any mode instead of
for approximately 5 seconds until HOLD time (3:00 only OFF mode. When the menu is entered with the keypad
indicating 3 hours) appears as a setting reminder. lockout feature enabled, the first menu item displayed is the
HOLD
3. After releasing the button, "HOLD
HOLD" on the display will combination code 0 . The or keys are used to set the
blink. combination unlock number from 0 to 999 999. If the unlock
4. Use or to set the temperature to your prefer number matches exactly with the combination lock number
ence. The thermostat will maintain this temperature stored in memory when the SYSTEM key is pressed, the
HOLD
setting for 3 hours with "HOLD
HOLD" blinking to remind you keypad is unlocked and the lock icon is removed. If the
it is in Temporary Hold. After 3 hours, the thermostat unlock number does not match when the SYSTEM key is
HOLD
HOLD"
will go back to the program temperature and "HOLD pressed, menu is exited and the keypad remains disabled.
will no longer blink or display.
To reset the combination code and unlock the keypad if the
Select F° or C° Readout – Changes the display readout to
11)Select code is forgotten, see troubleshooting section.
Centigrade or Fahrenheit as required.
Limited Heat Range – This feature provides a maximum
12)Limited
setpoint temperature for heat. The default setting is 90°F. It
can be changed between 62°F and 89°F by pressing the
or key.

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 CONFIGURATION MENU
Curtailment Menu Mode
The thermostat will be able to display information received from This menu will receive display information from the receiver.
the VHF remote signal utilizing the Curtailment Install menu. During the request the thermostat will display the curtailment
With the thermostat in the OFF Mode, press and together menu data. If failure to communicate to the receiver has
to enter the Installer/Configuration Menu, Then hold PRGM to COMM
occurred, the thermostat will display "COMM FAULT
COMM" and "FAULT
FAULT" on
put the thermostat into a Curtailment Menu Mode. the display for a second and will return to normal thermostat
Once activated, the thermostat will relinquish control of the operation. During this time, the normal communications fault
thermostat's display to the communications receiver and trans- procedure will be performed.
late any pushbutton selection to the receiver. This feature may
be exited by pressing RUN or when 120 seconds has elapsed
without keypad activity.

SPECIFICATIONS
ELECTRICAL DATA THERMAL DATA
Electrical Rating
Rating: Setpoint Temperature Range
Range:
20 to 30 VAC 50/60 Hz or DC 45°F to 90°F (7°C to 32°C)
0.2 to 0.8 Amps (Y1, E/W1, G Combined load) Operating Ambient Temperature Range
Range:
1.5 Amps (Y2, W2, O, B Load per terminal) 32°F to 105°F
2.5 Amps Maximum Total Load (All terminals combined) Operating Humidity Range
Range:
0 to 90% RH (non-condensing)
Shipping Temperature Range
Range:
-40°F to 150°F

OPERATION
The system "mode" is selected by pressing the SYSTEM Second Stage Time Delay
button. Icons on the bottom right corner of the display will Your thermostat is designed to determine the optimum time to
indicate the mode: COOL
COOL, AUTO
AUTO, HEAT
HEAT, EMER
EMER, or OFFOFF. In activate the second stage. Simply raising the temperature in
any mode except OFFOFF, the setpoint temperature will be shown heating or lowering it in cooling will not always force the
on the right side of the display. In OFF
OFF, this area will be blank.
thermostat to bring the second stage on quickly. There is a time
The current temperature will be displayed on the left side of the
delay from 0-30 minutes depending on the performance of the
display.
first stage of the system.
To operate properly in the AUTO mode, the heat setpoint
EXAMPLE: For the last 2 hours the thermostat is set on 70° and
temperature cannot be the same as or higher than the cool
the room temperature is 70° with the equipment using only the
setpoint temperature. The heat setpoint must be at least 1°
first stage of heat. Since the equipment is keeping the tempera-
lower than the cool setpoint.
ture within 1 degree of setpoint, the thermostat will delay
second stage for a longer time if you manually raise the
Automatic System Changeover temperature or if the room temperature quickly changes. Once
When the thermostat is in the AUTO mode, both "HEAT HEAT" and
HEAT the second stage comes on, it will come on sooner the next time
COOL
"COOL
COOL" are displayed. The thermostat will call for heat or cool there is a difference between the setpoint and the room
depending on the room temperature. The setpoint temperature temperature. The net effect of the staging program is that when
displayed will be that of the last mode called. If the last system the first stage is capable of making temperature the second
cycle was heat, the HEAT setpoint will be displayed. If the room stage will delay longer. When the thermostat calculates that
temperature raises above the HEAT setpoint and the COOL first stage cannot make temperature in a reasonable time, the
setpoint and a call for cool is required, the temperature dis- second stage will come on sooner. This built in function
played will change to be the COOL setpoint. automatically optimizes the use of additional stages of heat or
cool.

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 OPERATION
Manual Operation SAMPLE
Heating/Cooling Schedule Plan (Factory Program)
Permanent Program Override (HOLD HOLD
HOLD) – With the SYSTEM
WEEKDAYS SATURDAY SUNDAY
button set to HEAT or COOL
COOL, press the HOLD button once and (1 Day)
(5 Day) (1 Day)
HOLD
release. "HOLD
HOLD" will be displayed. Use or to adjust the
Start Start Start
temperature. The thermostat will hold the room temperature at Period
Time Temp Time Temp Time Temp
the selected setting until you press RUN button to start program
MORN 6:00 AM 70 F 6:00 AM 70 F 6:00 AM 70 F
operation again.

HEAT
DAY 8:00 AM 62 F 8:00 AM 62 F 8:00 AM 62 F
Temperature Override – Press or until the display
shows the temperature you want. The thermostat will override EVE 5:00 PM 70 F 5:00 PM 70 F 5:00 PM 70 F
current programming and keep the room temperature at the
NITE 10:00 PM 62 F 10:00 PM 62 F 10:00 PM 62 F
selected temperature until the next program period begins.
Then the thermostat will automatically revert to the program. MORN 6:00 AM 78 F 6:00 AM 78 F 6:00 AM 78 F

COOL
Temporary Program Override – The thermostat will override DAY 8:00 AM 85 F 8:00 AM 85 F 8:00 AM 85 F
current programming and keep the room temperature at the
EVE 5:00 PM 78 F 5:00 PM 78 F 5:00 PM 78 F
selected temperature for a programmed time period whenever
or keys are pressed. Once in the menu mode, press NITE 10:00 PM 82 F 10:00 PM 82 F 10:00 PM 82 F
or to change the time period.

PROGRAMMING YOUR THERMOSTAT Entering Your Program

This section will help you plan your thermostat's program to
Set Current Time and Day
meet your needs. For maximum comfort and efficiency, keep 1. Press TIME button once. The display will show the hour
the following guidelines in mind when planning your program. only.
• When heating (cooling) your building, program the temper-
atures to be cooler (warmer) when the building is vacant or EXAMPLE:
during periods of low activity.
• During early morning hours, the need for cooling is usually 2. Press and hold either or until you reach the
AM begins at mid-
correct hour and AM/PM designation (AM
minimal.
night; PM begins at noon).
Planning Your Program 3. Press TIME once again. The display window will show
the minutes only.
Look at the factory preprogrammed times and temperatures
shown in the sample schedule. If this program will suit your
needs, simply press the RUN button to begin running the EXAMPLE:
factory preset program.
If you want to change the preprogrammed times and tempera-
tures, follow these steps. 4. Press and hold either or until you reach the
correct minutes.
Determine the time periods and temperatures for your pro-
5. Press TIME once again. The display will show the day of
gram. You must program four periods for each day. However,
the week.
you may use the same heating and cooling temperatures for
6. Press or until you reach the current day of the
consecutive time periods. You can choose start times, heating
week.
temperatures, and cooling temperatures independently (for
7. Press RUN once. The display will show the correct time
example, you may select 5:00 AM and 70° as the weekday 1st
and room temperature alternately.
period heating start time and temperature and also choose
7:00 AM and 76° as the weekday 1st period cooling start time
and temperature). Enter Cooling Program
Use the table to plan your program time periods and the
temperatures you want during each period. Fill in the complete
! CAUTION
table to have a record of your programs. 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.
1. Press SYSTEM button to COOL.
2. Follow Enter Heating Program for entering your cooling
program, using your selected cooling times and tempera-
tures.

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 OPERATION
Heating/Cooling Schedule Plan
CHECK YOUR PROGRAMMING
WEEKDAYS SATURDAY SUNDAY
(5 Day) (1 Day) (1 Day) Follow these steps to check your thermostat programming
Start Start Start one final time before beginning thermostat operation.
Period
Time Temp Time Temp Time Temp 1. Press SYSTEM button to HEAT position.
MORN 2. Press PRGM to view the 1st weekday heating period
time and temperature. Each time you press PRGM, the
HEAT

DAY next heating period time and temperature will be display-

EVE ed in sequence for weekday, then Saturday and Sunday
program periods (you may change any time or tempera-
NITE ture during this procedure.
MORN 3. Press RUN.
4. Press SYSTEM button to COOL position.
COOL

DAY 5. Repeat step 2 to check cooling program.

EVE 6. Press SYSTEM button to HEAT or COOL and press
RUN to begin program operation.
NITE NOTE: Batteries are not required to keep your programming
or menu data. With two optional "AA" batteries installed,
Enter Heating Program your thermostat will maintain time and continuously
display the temperature during a loss of AC power.
1. Press the SYSTEM button to HEAT. Installed batteries will also allow programming prior to
2. Press PRGM once. "MOMO TU WE TH FR FR" (indicating installation.
weekday program) will appear in the display. Also dis-
played are the currently programmed start time for the YOUR THERMOSTAT IS NOW PROGRAMMED AND READY TO
1st heating period and the currently programmed temp- PROVIDE MAXIMUM COMFORT AND EFFICIENCY!
erature (flashing).

EXAMPLE:

This display window shows that for the 1st weekday

period, the start time is 6:00 AM and 68° is the program-
med temperature (this example reflects factory prepro-
gramming.
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 and 4 to select the start time and heating
temperature for the 2nd heating program period.
7. Repeat steps 3 through 5 for the 3rd and 4th heating
program periods.
8. Press PRGM once "SA SA
SA" (indicating Saturday program)
will appear in the display, along with the start time for the
1st heating period and the currently programmed temp-
erature.
9. Repeat steps 3 through 7 to complete Saturday heating
programming.
10.Press PRGM once to change to "SU SU
SU" (Sunday) heating
programming and repeat steps 3 through 7 to complete
Sunday programming.
11.When you have completed entering your heating pro-
gram, press RUN.

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 TROUBLESHOOTING
Reset Operation
If a voltage spike or static discharge blanks out the display or causes erratic thermostat operation, you can reset the
thermostat by removing the wires from terminals R and C and removing batteries for 2 minutes. After resetting the thermo-
stat, replace the wires and batteries. If the thermostat has been reset and still does not function correctly contact your
heating/cooling service person or place of purchase.
Pressing and and the SYSTEM keys at the same time will reset the thermostat to its factory default setting. This will
also clear any limited temperature ranges or keypad lockout settings. Note default system configuration is multistage system
operation.

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
HEAT. Set System Switch to HEAT and raise setpoint
above room temperature.
3. Loose connection to thermostat or Verify thermostat and system wires are securely
system. attached.
4. Furnace Lock-Out Condition. Heat Many furnaces have safety devices that shut down
may also be intermittent. when a lock-out condition occurs. If the heat works
intermittently contact the furnace manufacturer or
local service person for assistance.
5. Heating system requires service or Diagnostic: Set System Switch to HEAT and raise
thermostat requires replacement. 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 above. 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.
6. In power stealing mode, the Cut W25-W1 Jumper on thermostat subbase.
thermostat is stealing power from the
furnace and may be causing
unnecessary problems.
7. Thermostat may be in Load Shed. Wait for Curtailment Condition to end.

No Cool 1. System Switch not set to COOL

COOL. Set System Switch to COOL and lower setpoint
below room temperature.
2. Loose connection to thermostat or Verify thermostat and system wires are securely
system. attached.
3. Cooling system requires service or Same procedure as diagnostic for No Heat condi-
thermostat requires replacement. tion 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.
4. Thermostat may be in Load Shed. Wait for Curtailment Condition to end.

Heat, Cool or Fan 1. Possible short in wiring. Check each wire connection to verify they are not
Runs Constantly 2. Possible short in thermostat. shorted or touching together. No bare wire should
3. Possible short in heat/cool/fan stick out from under terminal screws. Try resetting
system. the thermostat as described above. If the condition
4. FAN Switch set to Fan ONON. 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.

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 TROUBLESHOOTING
Symptom Possible Cause Corrective Action
Furnace 1. The location of the thermostat and/or Digital thermostats normally provide precise
(Air Conditioner) the size of the Heating System may temperature control and may cycle faster than
Cycles Too Fast be influencing the cycle rate. some older mechanical models. A faster cycle rate
or Too Slow (narrow or means the unit turns on and off more frequently but
wide temperature swing) runs for a shorter time so there is no increase in
energy use. If you would like to increase the cycle
time, choose SL for slow cycle in the menu, step 4.
If an acceptable cycle rate is not achieved as
received or by choosing slow cycle, contact a local
service person for additional suggestions.

Thermostat Setting & 1. Thermostat thermometer setting The thermometer can be adjusted +/- 3 degrees.
Thermostat Thermometer requires adjustment. See Temperature Display Adjustment in the
Disagree Configuration Menu section.

Blank Display and/or 1. Voltage spike or static discharge. Use the Reset Operation at top of previous page.
Keypad Not Responding

Heat Setpoint will 1. The desired setpoint conflicts with the Change system mode to COOL. Raise the Cool
not Respond to the setpoint of the COOL mode. setpoint. Return to HEAT mode and set desired
Temperature Up Key temperature.

Cool Setpoint will 1. The desired setpoint conflicts with the Change system mode to HEAT. Lower the Heat
not Respond to the setpoint of the HEAT mode. setpoint. Return to COOL mode and set desired
Temperature Down Key temperature.

Forgot Keypad With the thermostat in any mode, press and at

Lockout Code the same time to enter the configuration menu at the
point where the lockout code is to be entered. Press
and and SYSTEM button at the same time to
reset the lockout code, unlock the keypad.

Why won't my 2nd or Your thermostat is designed to determine the

3rd stage come on? optimum time to activate the second stage. Simply
raising the temperature in heating or lowering it in
cooling will not always force the thermostat to bring
the second stage on quickly. There is a time delay
from 0-30 minutes depending on the performance
of the first stage of the system.

No Fan 1. In power stealing mode, the Cut W24-G Jumper on thermostat subbase.
thermostat is stealing power from the
fan and may be causing unnecessary
problems.

Antenna + Fault Icon 1. Communications from the receiver to Three finger reset.
the thermostat may be lost.

The Emerson logo is a

trademark and service mark
of Emerson Electric Co.

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