Lennox ComfortSense L7742U User guide

05/09 506228−01
*2P0509* *P506228-01*
E2009 Lennox Industries Inc.
Dallas, Texas, USA
Shipping and Packing List
1 − ComfortSense
®Model L7742U touch screen, 7−day program-
mable thermostat
2 − Mounting screws (M3.5x25mm self−tapping screws)
2 − Wall Anchors
1 each − Installation Quick-Start Guide, Programming & Application
Guide, Homeowner’s Manual, Warranty card, Warranty Audit tag
PROGRAMMING AND
APPLICATION GUIDE
ComfortSense®7000 Series
Model L7742U Touch Screen Programmable Thermostat
CONTROLS
506228−01
05/09
Supersedes 04/09
IMPORTANT
Read this manual before programming the thermostat.
Use this thermostat only as described in this manual.
IMPORTANT
In all applications, the ComfortSense®Model L7742U thermo-
stat can only be used with all residential units and approved
commercial split-system matches, and those which meet the
following installation criteria:
Sinstallation uses 18 GAUGE thermostat wire or larger,
Sthermostat wire run length DOES NOT EXCEED 300’ (91m),
Sload from any thermostat connection is 1 AMP or LESS.
If used with Harmony II®Zone Control System, consult Applica-
tion Note H−04−5.
Litho U.S.A.

506228−01 05/09 Page 2
Table of Contents
ComfortSense
®Model L7742U Thermostat 3. . . . . . . . . . . . .
Features 3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Touch Screen Display 4. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Home ScreenCurrent Conditions & Temp. Settings 5. . . . .
Controlling the Heat/Cool Modes of Operation 6. . . . . . . . . . .
Controlling the Fan Operation 7. . . . . . . . . . . . . . . . . . . . . . . . .
Controlling the Schedule 7. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Schedule TabProgramming 8. . . . . . . . . . . . . . . . . . . . . . . . .
Options TabReminders & User Settings 10. . . . . . . . . . . . . . .
Options TabInstaller Settings 13. . . . . . . . . . . . . . . . . . . . . . . .
Resetting Program to Factory Conditions 16. . . . . . . . . . . . . . .
EPA ENERGY STAR®Recommended Setpoints 17. . . . . . . . .
Humidification 19. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Dehumidification 21. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Humiditrol
®Enhanced Dehumidification Accessory (EDA) 22.
Stage Delay and Differential Settings 24. . . . . . . . . . . . . . . . . . .
Temporary Temperature Change (Pausing the Schedule) 31. .
Optional Remote Outdoor Sensor 32. . . . . . . . . . . . . . . . . . . . . .
Service Reminders 33. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Unit Part and Serial Numbers 33. . . . . . . . . . . . . . . . . . . . . . . . .
Memory Protection 33. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Appendix A. Flow Diagrams & Wiring Diagrams 34. . . . . . . . . .
Appendix B. Diagnostic Info. & Available System Settings 39.
NOTE − This thermostat is equipped with automatic compressor
protection to prevent potential damage due to short cycling or extended
power outages. The short cycle protection provides a 5−minute delay
between heating or cooling cycles to prevent the compressor from be-
ing damaged.
CAUTION
This is a 24VAC low−voltage thermostat. Do not install on volt-
ages higher than 30VAC.
Do not short (jumper) across terminals on the gas valve or at the
system control to test installation. This will damage the thermo-
stat and void the warranty.
WARNING
Always turn off power at the main power source by switching
the circuit breaker to the OFF position before installing or re-
moving this thermostat.
All wiring must conform to local and national building and elec-
trical codes and ordinances.
Do not switch system to cool if the outdoor temperature is be-
low 45°F (7°C). This can damage the cooling system.
These instructions are intended as a general guide and do not super-
sede local codes in any way. Consult authorities having jurisdiction be-
fore installation.
Check thermostat for shipping damage. If you find any damage, imme-
diately contact the last carrier.

Page 3 ComfortSensetModel L7742U Touch Screen 7−Day Programmable Thermostat
ComfortSense®Model L7742U Thermostat (Catalog No. Y2081)
Description
The ComfortSense®Model L7742U thermostat is an electronic 7−day
universal multi-stage programmable touch screen thermostat. It also
offers enhanced capabilities which include:
Shumidification measurement and control,
Sdew point adjustment control,
Sdehumidification measurement and control,
SHumiditrol
®Enhanced Dehumidification Accessory (EDA) capa-
bility,
Sequipment maintenance reminders,
Sworry−free memory storage feature,
Smenu−driven display.
This thermostat supports heat pump units or non−heat pump units, with
up to 4 stages of heating (dual fuel units) and 2 stages of cooling.
Dimensions
Screen dimensions: 3−7/16" (87 mm) width x 2−9/16" (65 mm) height
Case dimensions: 5−7/8" (149 mm) width x 4−9/16" (116 mm) height x
1−1/4" (31mm) depth
Features
Compressor Short Cycle Protection
A 5−minute compressor short cycle protection timer begins when a
compressor output is de−energized. Also, if a power loss occurs, the
system will go into compressor protection mode and display WAIT in
the display if there is a cooling or compressor heating call.
Outdoor Temperature Sensor
An outdoor temperature sensor (X2658) is required for dual fuel ap-
plications, balance points, dew point humidity control, and with Humidi-
trol®EDA.
In addition to measuring and displaying outdoor temperature, the out-
door sensor provides dew point adjustment and control for all models. If
used with this thermostat, the sensor enables optimal heating equip-
ment operation via programmable balance points.
NOTE − The outdoor sensor uses standard thermostat wiring; it
may be wired using two wires of a multi−wire cable.
When the outdoor sensor is connected, the temperature can be dis-
played in the information display area (see figure 2).
NOTE − For proper operation of Humiditrol®EDA applications, the out-
door sensor (X2658) MUST be installed.
L" Input
L" input from the equipment is used to notify the user of an outdoor
equipment fault by displaying HVAC ERROR DETECTED" when one
of the following conditions exist:
SL" terminal is activated with 24VAC and Y1 has been activated
for 5 minutes (units without LSOM, but which use Service Light
Monitor Kit), OR,
SLSOM error signal is detected on L" input and Y1 has been acti-
vated for 5 minutes.
NOTE − The L input is used for diagnostic information purposes only, it
is not intended to provide equipment protection.

506228−01 05/09 Page 4
Touch Screen Display
A
B
C
G
I
H
F
E
D
E
Figure 1. Touchscreen display
Press the screen anywhere − the first press turns on the backlight.
A Selection Tabs − Press to select: HOME (normal display),
SCHEDULE (for programming), OPTIONS (to set fan operation,
alerts, service reminders, and other user and installer settings).
B MODE − press to cycle through HEAT, COOL, AUTO
(autochangeover),OFF, EM HEAT (emergency heat).
C SCHED (schedule) − press to change between ON and OFF.
DDisplays room temperature.
EDisplays the current operation SET AT point(s). If MODE is set to
AUTO (autochangeover), both HEAT and COOL setpoints are
displayed.
FUp/down arrows used for adjusting temperature up or down; if in
AUTO (autochangeover) mode, two sets of up/down arrows ap-
pear.
GInformation display area, displays different information depending
on the tab selected:
DHOME tab: displays outdoor temperature (if outdoor sen-
sor X2658 is installed), indoor relative humidity (RH),
which mode is calling, hold settings information, service
reminders.
DSCHEDULE tab: displays the event being programmed;
DOPTIONS tab: displays a scrolling list of installer- and
user−adjustable parameters, including filter and service
reminder periods, etc.
HSchedule time adjustment, User/Installer Settings up/down ar-
rows:
DHOME screen: not visible except when executing a HOLD
SETTING)
DSCHEDULE and OPTION screens: used to adjust sched-
ule and option settings.
IDynamic keys − not visible in HOME screen unless executing a
HOLD SETTING. For SCHEDULE and OPTIONS settings, these
keys appear and change depending on the selection. See the
schedule and options sections for details.

Page 5 ComfortSensetModel L7742U Touch Screen 7−Day Programmable Thermostat
Home ScreenCurrent Conditions & Temperature Settings
INFORMATION
DISPLAY AREA
COOLING
TUE OCT 23 1:15PM
Figure 2. Home Screen
The HOME screen (figure 2) displays indoor temperature and outdoor
temperatureif the outdoor sensor is installed. Other system operational
information,such as indoor relative humidity (if turned on in user set-
tings), dehumidifying, cooling or heating, will alternately be displayed in
the information display.
Equipment operation information appears in the boxes along the left
side of the home screen to indicate cooling or heating equipment opera-
tion setting, and whether scheduled programming is ON or OFF. From
these boxes, users can change the unit’s mode to HEAT, COOL, AUTO
(autochangeover− default), EM HEAT (emergency heat for heat pump
applications including dual fuel and HP with Electric Heat), or OFF.
The user can also decide whether to operate the unit per the program-
mable schedule, or in a non−programmable mode using the SCHED
box.

506228−01 05/09 Page 6
Controlling Heat/Cool Modes of Operation
On initial power up or after an a power loss over 2
hours, the thermostat powers up at the HOME
screen in the AUTO position. If it powers up after a
power loss of less than 2 hours, it assumes the last
mode set. Pressing MODE repeatedly scrolls
through all the modesAUTO, EM HEAT, COOL,
HEAT, then back to OFF.
HEAT, COOL and OFF modes are as each name implies. AUTO
(autochangeover) allows the thermostat to switch between Heating
and Cooling, whichever mode is dictated by the indoor temperature.
EM HEAT (emergency heat) bypasses the first stage of heating (any
stage[s] of heat pump heating) and goes directly to the heat stage used
for maximum heating to more quickly warm a very cold house.
When the indoor temperature decreases or increases, the HEATING or
COOLING cycle will turn on based on the displayed mode. When the
HVAC system is on, the INFORMATION DISPLAY AREA (shown in fig-
ure 3) will display one or several operational messages (listed in the
table below). If the outdoor sensor is connected and is turned on in user
settings, outdoor temperature will be included in the displays. The table
below summarizes the information messages.
When the faults, errors, and service information displays appear, dy-
namic keys will appear under the second line entries, REMIND,
CLEAR, SERVICE, or RESET. Press the box to perform the action.
INFORMATION DISPLAY AREA
Figure 3. Home Screen
Information Display Area table
Faults, Errors, and Service Information Operating Information
TEMP SENSOR ERROR, MEMORY ERROR
CALL FOR SERVICE
Top line: fault/error
Bot. line: action
SET DATE/TIME
Default DATE/TIME (MON JAN 1 12:00 PM)
[First time start up msg]
NO OUTDOOR SENSOR
CALL DEALER INFO
Top line: fault/error
Bot. line: action
HEATING, COOLING, HUMIDIFYING, DEHUMIDIFYING,
SYSTEM OFF, OUTDOOR TEMP xxF, INDOOR RH xx%,
MON SEP 24 3:OO PM
Top line: operation msgs
Bottom line: date & time
REPLACE: MEDIA FILTER; UV LAMP; HUM PAD; METAL INSERT
REMIND RESET
Top line: serv. req’d
Bot. line: action
SCHEDULE ON, SCHEDULE OFF, WAIT, FAN ON, FAN CIRC
MON SEP 24 3:OO PM
Top line: operation msgs
Bottom line: date & time
ROUTINE SYS CHECK−UP
REMIND RESET
Top line: serv. req’d
Bot. line: action
HOLD SETTING UNTIL PRESS SCHED TO
MON SEP 24 3:OO PM RESUME PROGRAM
[Alternating msgs during
a held schedule]
NO OUTDOOR SENSOR, HUM SENSOR ERROR, HVAC ERROR DETECTED
REMIND SERVICE
Top line: fault/error
Bot. line: action
DEALER INFORMATION (Edited to show dealer contact informa-
tion [2 lines])
Contact
Installing Dealer

Page 7 ComfortSensetModel L7742U Touch Screen 7−Day Programmable Thermostat
Controlling the Fan Operation
Fan Modes
If backlight is not on continuous, press the screen
anywhere to turn on the backlight. Press the
OPTIONS tab to access the FAN mode control.
Press FAN button; repeated presses scroll through
all the modes, AUTO, ON, and CIRC (circulate).
SAUTOthe fan is following schedule.
SONthe fan is NOT following the schedule and runs continuously
until it is changed from the OPTIONS screen.
SCIRCthe fan is following schedule and cycles during periods of
equipment inactivity. Cycle time is dependent on user settings
FAN CIRCULATE (Page 11).
If FAN mode displays AUTO and ON or CIRC was selected during
scheduling for the current period, the thermostat will indicate the current
fan mode in the information display (FAN ON or FAN CIRC).
In the CIRC mode, the user can cycle the fan for a programmed
percentage of active time per hour, during periods of equipment
inactivity (i.e., heating or cooling equipment not running). The fan is ON
for 5 minutes at a time. The user may change the percentage of ON time
that the fan is on (see FAN CIRCULATE [Page 11]):
Fan Program
The user can program the fan to be ON, AUTO, or CIRC during a
program event period. While scheduling the event, if the fan is set to
ON, it will remain on during the entire event. If it is set to CIRC, it will
circulate during equipment inactivity per user programmable cycles
(see FAN CIRCULATE, Page 11). If set to AUTO, the fan will come on
with the equipment to serve the heating/cooling demand and go off
accordingly.
NOTE − When the OPTIONS screen FAN mode is changed to ON or
CIRC, whatever was scheduled is ignored − the fan will either be ON or
it will CIRCULATE per the user−programmed intervals (USER
SETTINGS − FAN CIRCULATE (Page 11). When FAN − AUTO is
selected in the OPTIONS screen, the schedule is followed.
Controlling the Schedule
If backlight is not on continuous, press the screen
anywhere to turn on the backlight.
From the HOME screen press SCHED; repeated
presses toggle the schedule ON and OFF. If ON, the
system follows the program developed by the user
(Page 8).
If OFF, the system operates as a non−programmable thermostatthe
user must make changes when desired. The autochangeover feature
continues to operate based on the manual user inputs.
The fan mode is displayed on the SCHEDULE screen when program-
ming the thermostat and can be changed only during schedule editing
(after EDIT is pressed). Fan settings in OPTIONS screen will OVER-
RIDE the scheduled fan operation.

506228−01 05/09 Page 8
Schedule tabProgramming
If backlight is not on continuous, press the screen anywhere to turn on
the backlight. Press the SCHEDULE tab along the top of the screen.
The display changes to programming mode (figure 4) and shows the
current settings.
EVENTS DAILY 2 OR 4The thermostat may be programmed for two
or four (default) events per day. The names for the events are: WAKE,
LEAVE, RETURN, and SLEEP. The selected time for an event to occur
is based on when you want the event to begin. Four events (default) are
common for working households. To change to two events per day, see
page 11. When set for two events per day, the display would appear as:
WAKE (or SLEEP) PERIOD BEGINS".
WAKE PERIOD BEGINS
5:OOAM
Figure 4. Schedule Screen
Programmingmay be performed in groups of days or individual days,
as follows:
AMON TO SUN − allows every day to be set the same.
BMON TO FRI (weekday programming) and
SAT TO SUN (weekend programming).
CMONDAY through SUNDAY allows individual days of the week to be
programmed separately.
NOTE − After using one of the groups of days described above, the
program allows you to subsequently change individual days to suit your
needs.
To get to the different groupings of days, press EDIT, then press NEXT
repeatedly to scroll to the desired grouping.
Programming Complexity
The programming process for groups of days or individual days is the
same, except in the amount of times required to go through the process.
Full WeekThe least complex program is the full week MON TO
SUN" program, wherein the events for every day of the week are the
same. This requires one time through the event programming process.
Work WeekNext in complexity to the full week program is the work
week program wherein the events are set for a typical work week (MON
TO FRI) and different events are set for the weekend (SAT TO SUN).
This requires two times through the events.
Day by DayMost complex because this requires going through the
programming process 7 times.

Page 9 ComfortSensetModel L7742U Touch Screen 7−Day Programmable Thermostat
Schedule tabProgramming (continued)
Days & Events Programming process
Action Display shows...
1 Press SCHEDULE tab SCHEDULE screen
2 Press EDIT UP/DOWN arrows on right−hand
side of screen; EDIT changes to
CANCEL
3 Press NEXT to highlight the de-
sired grouping of days
Days change to match selected
group, e.g. MON TUE WED THU FRI
4 Press an event: WAKE (default),
LEAVE, RETURN, & SLEEP to
select for programming
Filled triangle above event
indicates which event is selected
for change
5 Press UP/DOWN arrows to
select desired temperature
After change is made, SAVE
appears in the bottom right−hand
of the screen
6 Press FAN repeatedly to select
desired fan mode
Fan indicator displays selection
(ON, AUTO, or CIRC)
7 Press UP/DOWN arrows to
adjust start time for
selected event
Information area displays start
time
8 Repeat steps 4 − 7 for all remaining events.
(If you selected other than MON TUE WED THU FRI SAT SUN), continue;
otherwise, skip to step 11.
9 Press NEXT for the next group
or the next day
Days change to match selected
group, e.g. SAT SUN
10 Repeat steps 3 through 8 for the remaining days, if necessary.
11 Press SAVE when all events and
days are programmed as desired
The changes are made and the
schedule screen reappears.
24
6
1
7
5
WAKE PERIOD BEGINS
5:OOAM
911
3
Figure 5. Programming days and events

506228−01 05/09 Page 10
Options tabReminders/User Settings
CLEAN button [OPTIONS TAB > [CLEAN] ]
When you select the OPTIONS tab, two buttons appear near the bot-
tom of the screen labeled CLEAN and ENTER. Press the CLEAN but-
ton to deactivate the touch" zones for 30 seconds. Clean the screen
with a soft cloth and a mild glass cleaning solution.
The Options screen provides user and installer access to the various
features for setup and access to the reminders.
REMINDERS
USER SETTINGS
Reminders [OPTIONS TAB > REMINDERS > [ENTER] ]
Set timers from 1 to 24 months in either calendar time or system run
time. Reminders appear when it is time to service the following (for
more details on REMINDERS, see Page 33):
REPLACE MEDIA FILTER
DUE FRI JUN 12 O9
REPLACE UV LAMP
DUE FRI SEP 11 O9
ROUTINE SYS CHECK−UP
DUE IN 216O HOURS
PURE AIR MAINTENANCE
DUE FRI SEP 11 O9
REPLACE HUM PAD
DUE FRI JUN 12 O9
(CUSTOM REMINDER 1)
DUE WED OCT 21 09
User Settings [OPTIONS TAB > USER SETTINGS > [ENTER] ]
12 OR 24 HOUR Page 10
BACKLIGHT INTENSITY Page 12
BACKLIGHT SETTING Page 12
COOLING LIMIT Page 12
DATE/TIME Page 10
DISPLAY INFO Page 11
EVENTS DAILY 2 OR 4 Page 11
F/C Page 10
FAN CIRCULATE Page 11
HEATING LIMIT Page 12
HUMIDITROL ADJUST Page 12
HUMIDITY SETTING Pages 12, 20, 22
SECURITY LOCK Page 12
VIEW CONTACT INFO Page 11
Press the OPTIONS tab; use the arrows to select USER SETTINGS.
Press ENTER.
USER SETTINGS
INSTALLER SETTINGS
The following items are available for modifying. Follow the instructions
for each parameter.
DATE/TIMESet month, day, year, hour, and minute using DATE/
TIME option. Select DATE/TIME; press ENTER. Small, filled up-arrow
is the selected column; use up/down arrows to adjust; press box below
each small up-arrow to select each column. Adjust; press SAVE.
FEB 11 2OO9 12PM 49
MON DAY YR HR MIN
CANCEL||||||SAVE|
F/Cdefault is Fahrenheit; to change to Celsius, scroll to F/C; press
ENTER. Use arrows to change to C; press SAVE.
F OR C
DEFAULT(F) F
12 OR 24 HOUR clockdefault is 12H; to change, scroll to 12 OR 24
HOUR; press ENTER. Use arrows to change to 24H; press SAVE.
12 OR 24 HOUR
DEFAULT(12HR) 12H

Page 11 ComfortSensetModel L7742U Touch Screen 7−Day Programmable Thermostat
Options tabUser Settings (continued)
EVENTS DAILY 2 OR 4default is 4; to change, scroll to EVENTS
DAILY 2 OR 4; press ENTER. Use arrows to change to 2; press SAVE.
EVENTS DAILY 2 OR 4
DEFAULT(4) 2
VIEW CONTACT INFOscroll to VIEW CONTACT INFO from the
user settings menu; press ENTER. Use BACK to return to menu. (To
set this to display on the home screen, see DISPLAY INFO.)
DISPLAY INFOcontrols what is displayed in the field below the tem-
perature and above the time on the HOME screen; it may display OUT-
DOOR TEMP, INDOOR RH (relative humidity), and CONTACT INFO
or any combination of the three, or none if all three are set to OFF.
Scroll to DISPLAY INFO; press ENTER. Use arrows to select OUT-
DOOR TEMP. INDOOR RH or CONTACT INFO; press ENTER.
DISPLAY INFO
OUTDOOR TEMP
INDOOR RH
CONTACT INFO
NOTE − When turning ON the OUTDOOR TEMP option OUT-
DOOR SENSOR REQUIRED" will display if the physical sensor
is not installed.
NOTE − If outdoor sensor is not present and if user tries to select the
options DISPLAY INFO −> OUTDOOR TEMP or HUMIDITROL a mes-
sage is displayed OUTDOOR SENSOR REQUIRED" instead of scroll
options for these menus. Information about installing the sensor is de-
scribed on Page 32.
For OUTDOOR TEMP, select ON or OFF; then press SAVE.
OUTDOOR TEMP
DEFAULT(OFF) ON
For INDOOR RH, use arrows to select ON or OFF; then press SAVE.
INDOOR RH
DEFAULT(OFF) ON
For CONTACT INFO, select ON or OFF; then press SAVE.
CONTACT INFO
DEFAULT(OFF) ON
FAN CIRCULATEAs an option to running the fan all the time, fan cir-
culate allows the user to decide how much the fan will run during peri-
ods of equipment inactivity. The fan ON time is always set to 5 minutes.
This option will cause the fan to come on more or less frequently. The
default is 35%; to change, scroll to FAN CIRCULATE; press ENTER.
Use arrows to change to 15, 25, or 45%; press SAVE.
FAN CIRCULATE
DEFAULT(35%) 25%
15% (9 minutes fan run time per hour)
25% (15 minutes fan run time per hour)
35% (21 minutes fan run time per hour)
45% (27 minutes fan run time per hour).

506228−01 05/09 Page 12
Options tabUser Settings (continued)
COOLING LIMITThis limits the temperature at which the thermostat
may be set for cooling (default is 50º); to change to any degree between
45ºF and 90ºF, scroll to COOLING LIMIT; press ENTER. Use arrows to
change to desired temperature; press SAVE.
COOLING LIMIT
DEFAULT(5O°F) 55°F
HEATING LIMITThis limits the temperature at which the thermostat
may be set for heating (default is 85º); to change to any degree between
45ºF and 90ºF, scroll to HEATING LIMIT; press ENTER. Use arrows to
change to desired temperature; press SAVE.
HEATING LIMIT
DEFAULT(85°F) 80°F
HUMIDITY SETTINGSee separate sections − Humidify (Page 20)
and Dehumidify (Page 22).
HUMIDITROL ADJUSTIf Humiditrol®is enabled in the installer set-
tings, then this adjustment affects overcooling operation. Overcooling
ranges from 2ºF below the cooling setpoint (MIN setting) down to 2ºF
above the heating setpoint (MAX setting). Halfway between the two
settings is the MID setting. The default setting is MAX; to change to MID
or MIN, scroll to HUMIDITROL ADJUST; press ENTER. Use arrows to
scroll to MID or MIN; then press SAVE.
HUMIDITROL ADJUST
DEFAULT (MAX) MIN
NOTE − Humiditrol®does not function if the outdoor temperature is 95ºF
or greater nor when the indoor temperature is 65ºF or less.
BACKLIGHT SETTINGdefault is POWER SAVE; scroll to BACK-
LIGHT SETTING; press ENTER. Use arrows to change to CONTINU-
OUS; press SAVE.
BACKLIGHT SETTING
DEF(SAVE) POWER SAVE
BACKLIGHT INTENSITYdefault is 100%; scroll to BACKLIGHT IN-
TENSITY; press ENTER. Use arrows to change to 20 to 100% in 20%
increments; press SAVE.
BACKLIGHT INTENSITY
DEFAULT(1OO%) 8O%
SECURITY LOCKdefault − no locks at all − this provides two methods
of locking the thermostat:
Answer YES to ALLOW TEMP ADJUSTanyone can make tem-
perature setpoint changes without entering a 3−digit code.
Answer NO to ALLOW TEMP ADJUSTprevents making any
changes at all until the 3−digit code is entered.
Scroll to SECURITY LOCK and press ENTER; ALLOW TEMP AD-
JUST screen appears; press box below YES or NO.
ALLOW TEMP ADJUST
YES NO
CANCEL|||
The ENTER LOCK CODE screen appears.
ENTER LOCK CODE
OOO
CANCEL||||SAVE|
To enter the lock code, press box below each small up-arrow to select
each column. Use up/down arrows to enter a number, then press the
box below the next number and repeat to enter a 3-digit lock code; write
down the number for future reference; press SAVE.
NOTE − If the security code is forgotten or misplaced, use the universal
code 864" to unlock.

Page 13 ComfortSensetModel L7742U Touch Screen 7−Day Programmable Thermostat
Options tabInstaller Settings
Installer Settings
[OPTIONS TAB > INSTALLER SETTINGS > [ENTER] [ENTER] ]
COMPRESSOR PROTECT Page 17
CONTACT INFORMATION Page 16
CUSTOM REMINDERS Page 16
DAYLIGHT SAVING TIME Page 16
DEADBAND Page 14
DEHUMIDIFICATION Page 21
DIFFERENTIAL SETTINGS Page 24
ENERGY STAR DEFAULT Page 17
H/C STGS LOCKED IN Page 25
HIGH BALANCE POINT Page 14
HUMIDITY OFFSET Page 17
HUMIDITY SETTING Page 14
HUMIDIFICATION Page 19
LOW BALANCE POINT Page 14
RESET SETTINGS Page 16
RESIDUAL COOL Page 14
SMOOTH SET BACK Page 14, Page 15
SSR STG2 LOCK OUT Page 14
STAGE DELAY/DIFFERENTIAL
SETTINGS Page 14, Page 24
STG 1 DIFF Page 24
STG 2 DIFF thru STG 4 DIFF Page 24
STG DELAY TIMERS Page 24
STG2 HP LOCK TEMP Page 25
SYSTEM SETUP Page 13
SYSTEM TEST MODES Page 18
TEMPERATURE OFFSET Page 17
Press OPTIONS tab for the main options screen, then use the arrows to
select INSTALLER SETTINGS. Press ENTER.
INSTALLER SETTINGS
−−−−−−−−−−−−−−−−−−−−
After the first ENTER, the following appears:
MUST BE SET BY
QUALIFIED PERSON
Press ENTER again to access installer settings. (CANCEL returns to
the main OPTIONS screen.)
The following items may be modified. Follow the instructions for each
parameter. Note that some options will not appear for all setups (e.g.
only Heat Pumps will have Low and High Balance Points; otherwise,
these do not appear).
SYSTEM SETUPSets the thermostat for operation with a heat pump
or non-heat pump and defines the number of compressor stages and
the number of backup heat stages. The default settings for the system
are Non−heat Pump, Gas/Oil, 2 compressor stages, 2 indoor heat
stages.
Use arrows to select from the list; then press ENTER.
SYSTEM SETUP
NON HEAT PUMP
HEAT PUMP
COMPRESSOR STAGES
INDOOR HEAT STAGES
For NON HEAT PUMP, use arrows to select backup heat: NO HEAT,
GAS/OIL, or ELECTRIC; then press SAVE.
NON HEAT PUMP
NO HEAT
GAS/OIL
ELECTRIC
For HEAT PUMP, use arrows to select backup heat: NO BACKUP
HEAT, DUAL FUEL (GAS/OIL), or ELECTRIC; then press SAVE.
HEAT PUMP
NO BACKUP HEAT
DUAL FUEL (GAS/OIL)
ELECTRIC
For COMPRESSOR STAGES, use arrows to select either 1 or 2 com-
pressor stages; then press SAVE.
COMPRESSOR STAGES
2
For INDOOR HEAT STAGES, use arrows to select 1 or 2 indoor heat
stages; then press SAVE.
INDOOR HEAT STAGES
2

506228−01 05/09 Page 14
Options tabInstaller Settings (continued)
RESIDUAL COOLdefault is zero seconds. This is the time, in sec-
onds, that the fan runs after a call for cooling is satisfied in order to deliv-
er any residual cooling ability from the coil and ductwork into the condi-
tioned space. Scroll to RESIDUAL COOL; press ENTER. Use arrows
to select seconds: 0, 30, 60, 90, and 120; press SAVE.
RESIDUAL COOL
DEFAULT(OS) 6OS
LOW BALANCE POINTdefault 25°F (heat pump only, and if outdoor
sensor installed). If outdoor temperature is below programmed Low
Balance Point, compressor heating is not allowed. Use arrows to select
OFF or any point from −20°F to the High Balance Point setting in 1.0°F
steps; press SAVE.
LOW BALANCE POINT
DEFAULT(25°F) 25°F
HIGH BALANCE POINTdefault is 50°F (heat pump only, and if out-
door sensor installed). If outdoor temperature is above the High Bal-
ance point, then auxiliary heat is not allowed. High Balance Point can-
not be set closer than 2°F above the Low Balance Point. For example, if
LBP is 25°F, HBP must be at least 27°F. Use arrows to select OFF or
any point from the Low Balance Point up to 75°F in 1.0°F steps; press
SAVE.
HIGH BALANCE POINT
DEFAULT(5O°F) 45°F
DEADBANDdefault is 4°F. The deadband setting is the minimum dif-
ference between the cooling and heating setpoints. This setting is used
in autochangeover mode to ensure smooth equipment operation and
allows for flexibility in Humiditrol®EDA operation. The deadband is ad-
justable from 3 to 8°F.
DEADBAND
DEFAULT(4°F) 5°F
SMOOTH SET BACK(SSR) default is OFF. When enabled, smooth
set back begins recovery up to 2 hours before the programmed time so
that the programmed temperature is reached at the corresponding pro-
grammed event time. Assume 12°F per hour for first stage gas/electric
heating and 6°F per hour for first stage compressor based heating or
cooling. With Smooth Set Back disabled, the control will start a recov-
ery at the programmed time. Scroll to SMOOTH SET BACK; press EN-
TER. Use arrows to select between ON or OFF. Press SAVE.
SMOOTH SET BACK
DEFAULT(OFF) ON
NOTE − Smooth Set Back and STG2 Lock Out operations vary de-
pending on equipment. See table 1 on Page 15.
SSR STG2 LOCK OUT[not available if SMOOTH SET BACK is
OFF] default is 20 minutes. Scroll to SSR STG2 LOCK OUT; press EN-
TER. Use arrows to select OFF or the number of minutes before the
programmedevent time that stage 2 is allowed to operate (OFF or 20 to
120 minutes in 10 minute increments). Press SAVE.
SSR STG2 LOCK OUT
DEFAULT(2OMIN) 4OMIN
HUMIDITY SETTINGSee separate sections − Humidification
(Page 19) and Dehumidification (Page 21).
STAGE DELAY AND DIFFERENTIAL SETTINGSThe differential or
delay settings in the Installer Settings menu are:
STG DELAY TIMERS
STG 1 DIFF
STG 2 DIFF
STG 2 DELAY
STG 3 DIFF
STG 3 DELAY
STG 4 DIFF
STG 4 DELAY
H/C STGS LOCKED IN
STG 2 HP LOCK TEMP
See Page 24 for more stage delay and differential details.

Page 15 ComfortSensetModel L7742U Touch Screen 7−Day Programmable Thermostat
Options tabInstaller Settings (continued)
Table 1. Smooth Set back Recovery (SSR) & SSR Stg 2 Lock Out Operation
Equipment Available SSR = Enabled; SSR Stg 2 lock out = enabled SSR = Enabled; SSR Stg 2 lock−out = disabled (off)
1 stage HP with 1 or 2 stages
elec backup
Run HP (Y1) only; all backup heat (W1/W2) enabled 20
− 120 min before wake up setpoint
Run HP (Y1) and have available backup heat (W1/W2) as needed.
2 stage HP with 1 or 2 stages
elec backup
Run HP (Y1/Y2) only; all backup heat (W1/W2) enabled
20 − 120 min before wake up setpoint
Run HP (Y1/Y2) and have available backup heat (W1/W2) as needed.
1 stage HP with 1 stage gas/oil
backup
Run HP (Y1) only; all backup heat (W1) enabled 20 −
120 min before wake up setpoint
Run HP (Y1) until a 2nd stage demand is needed (by time/temp. differential); then HP
operation must stop and changeover and lock in to W1 heat until setpoint reached.
1 stage HP with 2 stages gas/oil
backup or modulation furnace
Run HP (Y1) only; all backup heat (W1/W2) enabled 20
− 120 min before wake up setpoint
Run HP (Y1) until a 2nd stage demand is needed (by time/temp differential); then HP
operation must stop and changeover to W1/W2 heat as needed; lock in W1/W2heat
until setpoint reached.
2 stage HP with 1 stage gas/oil
backup
Run HP (Y1/Y2) only; all backup heat (W1/W2) enabled
20 − 120 min before wake up setpoint
Run HP (Y1/Y2) until a 2nd stage demand is needed (by time/temp. differential); then
HP operation must stop & changeover and lock in to W1 heat until setpoint reached
2 stage HP with 2 stages gas/oil
backup or modulation furnace
Run HP (Y1/Y2), all backup heat (W1/W2) enabled 20 −
120 min before wake up setpoint
Run HP (Y1/Y2) until a 2nd stage demand is needed (by time/temp. differential); then
HP operation must stop & changeover and lock in to W1/W2 heat until setpoint
reached.
2 stages gas/oil heat or modula-
tion furnace
Run W1 only; W2 enabled 20 − 120 min before wake up
setpoint
Run W1 heat and bring on W2 heat until setpoint reached.
1 stage cooling Run Y1 to wake up set point Run Y1 heat until setpoint reached.
2 stage cooling Run Y1 during recovery enable Y2 field wake up set
point
Run Y1 & Y2 heat as needed until setpoint reached.

506228−01 05/09 Page 16
Options tabInstaller Settings (continued)
DAYLIGHT SAVING TIME (DST)default setting is ON (enabled).
Note: Beginning in 2007, DST will begin on the second Sunday in March
and end the first Sunday in November. In the U.S., clocks spring for-
ward from 1:59 a.m. to 3:00 a.m.; in fall, clocks fall back from 1:59 a.m.
to 1:00 a.m. If the community or state opts out of DST, turn this OFF.
Scroll to DAYLIGHT SAVING TIME; press ENTER. Use up/down ar-
rows to select OFF. Press SAVE.
DAYLIGHT SAVING TIME
DEFAULT(ON) OFF
CONTACT INFORMATIONdefault is CONTACT INSTALLING
DEALER. Contact information will appear under user menu, and re-
minder screen information buttons. Also can be set to scroll on home
screen when set up under user menu.
This may be programmed with the dealer or technical service contact.
Scroll to CONTACT INFORMATION; press ENTER. A cursor appears
to the left of the first line. Use arrows to select letters, numbers, and spe-
cial characters. When the first character is identified, press NEXT to ad-
vance to the next character; repeat to input the desired contact informa-
tion. Press SAVE when finished.
CONTACT
INSTALLING DEALER
CUSTOM REMINDERSTwo additional reminders may be created
using a text message. This will appear in the list of reminders and the
user can then select the time for the reminder to be displayed. Scroll to
CUSTOM REMINDER 1 or 2. Press ENTER. To create a reminder,
press EDIT.
CUSTOM REMINDER 1
A cursor will appear on the second line. Use the arrows to scroll through
letters, numbers and special characters. When the desired character
appears, press NEXT to advance to the right by one character. Contin-
ue until the message is complete (up to 19 characters). When finished,
press SAVE.
CUSTOM REMINDER 1
CLEAN OUTDOOR UNIT
RESET SETTINGSTo reset the ComfortSense®Model L7742U ther-
mostat to factory defaults, scroll to RESET SETTINGS.
IMPORTANT
RESET SETTINGS erases all programming and returns the ther-
mostat to the factory conditions, including the installer set-
tings. Use this only as a last resort.
With RESET SETTINGS selected, press ENTER. Press the box below
YES to reset; RESETTING SETTINGS TO DEFAULTS appears briefly
and then returns to the INSTALLER SETTINGS list.
RESET SETTINGS
YES NO
||

Page 17 ComfortSensetModel L7742U Touch Screen 7−Day Programmable Thermostat
Options tabInstaller Settings (continued)
ENERGY STAR DEFAULTEPA ENERGY STAR®recommended
setpoints for heating and cooling can help the household save energy.
The following time and temperatures are preprogrammed into the con-
trol to conform to Energy Star requirements.
Table 2. ENERGY STAR®Setpoints
NOTE − Humidification
and dehumidification are
not part of the ENERGY
STAR®program. A higher
utility bill may occur
when not using the set-
points in this table.
Time Heating Cooling
Wake 70°F (21°C) 78°F (25°C)
Leave 62°F (17°C) 85°F (29°C)
Return 70°F (21C) 78°F (25°C)
Sleep 62°F (17°C) 82°F (28°C)
Scroll to ENERGY STAR DEFAULT; press ENTER. Press the box be-
low YES to reset; ENERGY STAR SETTING" appears briefly and then
returns to the installer setting listing.
ENERGY STAR DEFAULT
YES NO
||
TEMPERATURE OFFSETdefault is 0°F. This setting can be used to
offset the displayed space temperature by up to +/− 5°F. This offset also
applies to the control temperature. Scroll to TEMPERATURE OFFSET;
press ENTER. Use arrows to select a new offset. Press SAVE.
TEMPERATURE OFFSET
DEFAULT(O°F) 3°F
HUMIDITY OFFSETdefault is 0%. This can be used to offset the dis-
played and controlled space relative humidity (RH) by up to +/− 10%
RH. Scroll to HUMIDITY OFFSET; press ENTER. Use arrows to select
a new offset. Press SAVE.
HUMIDITY OFFSET
DEFAULT(O%) 2%
See separate section (Page 24) for details.
COMPRESSOR PROTECTdefault is ON; it may be turned OFF,
however, after one compressor cycle, it will revert back to ON. If the
system is running in compressor protection, the home screen displays
WAIT" only if there is cooling or heating call for the compressor
(Y1/Y2). If compressor protection is running and there is a demand for
electric heating, the system waits for the compressor protection timer to
expire. Scroll to COMPRESSOR PROTECT; press ENTER. Use up/
down arrows to select OFF. Press SAVE.
COMPRESSOR PROTECT
DEFAULT(ON) OFF

506228−01 05/09 Page 18
Options tabInstaller Settings (continued)
SYSTEM TEST MODESAfter the thermostat has been installed and
set−up, the installer may run a system test function (accessed through
the installer settings menu), to test all cooling, heating, Emergency
Heating stages and FAN outputs. Scroll to SYSTEM TEST MODES
and press ENTER; select TEST OUTPUTS and press ENTER.
SYSTEM TEST MODES
TEST OUTPUTS
SCROLL arrows move through a list of all signals, Y1 ON, Y1 OFF, Y2
ON, Y2 OFF, etc. With a signal displayed, press ENTER to start the
test, (e.g. Y1 ON selected, press ENTER brings on Y1; Y1 OFF se-
lected, press ENTER shuts off Y1. CANCEL, pressed at anytime dur-
ing tests will return the previous screen and also disable any test and
puts the thermostat back into normal mode.
NOTICE
Risk of equipment damage.
Can cause compressor failure.
In dual fuel system applications, do not turn on heat pump and
furnace at the same time in system test mode.
All HVAC components can be tested to confirm the signals between
thermostat and unit are being sent and were received.
NOTES − After 5 minutes without a test being initiated, the test modes is
disabled and system goes back to the normal mode (i.e. HOME
screen).
When in SYSTEM TEST MODE, the compressor minimum off timer is
bypassed.
TEST OUTPUTS
OFF
Y1 ON
Y1 OFF
Y2 ON
Y2 OFF
W1 ON
W1 OFF
W2 ON
W2 OFF
FAN (G) ON
FAN (G) OFF
H ON
H OFF
D ON
D OFF
O ON (B OFF)
B ON (O OFF)

Page 19 ComfortSensetModel L7742U Touch Screen 7−Day Programmable Thermostat
Humidification
INSTALLER SETTINGS
Humidification(adding moisture to air) is provided only when the ther-
mostat is in heat mode. The humidification signal (H terminal) to the hu-
midifier (off when the thermostat is in the COOL mode) controls humidi-
fication. When the thermostat is powered, the H terminal is normally
inactive (open circuit) in any mode (HEAT, COOL, OFF). When a hu-
midification demand is present, H terminal and G terminal are ener-
gized (24V).
HUMIDITY SETTINGdefault OFF. Installer settings must be
turned on before the user will have control over the humidity. The
mode selected determines how the user can adjust the relative humid-
ity (RH). The installer settings include BASIC, PRECISION, DEW-
POINT, and OFF.
BASIC & PRECISIONthese thermostat modes allow the user to con-
trol the relative humidity (RH) between 15 and 45%. The following con-
ditions must be met for either mode to operate:
Shumidification mode has been enabled, and
Sthe unit is in HEAT mode, and
Shumidification demand exists (24V present at H), and
Additionally, the BASIC mode requires:
Sheat demand exists (Y energized for heat pump heating, or W en-
ergized for gas heat [W may be energized with G de−energized]).
Scroll to HUMIDITY SETTINGS; press ENTER. Press the box below
HUMIDIFY.
HUMIDITY MODE
HUMIDIFY DEHUMIDIFY
||
Use up/down arrows to select BASIC or PRECISION; press ENTER.
HUM MODE SETTING
DEF(OFF) PRECISION
Default setting is 45% RH. Use up/down arrows to define what NEW
SETPOINT IS (between 15 to 45%); then press SAVE.
HUM SETPOINT
DEFAULT (45%) 4O%
DEW POINTDew point adjustment mode will change the humidifica-
tion setpoint based on the outdoor temperature and a user−defined dew
point adjustment setting.
NOTE − In dew point adjustment mode, the humidification setpoint has
no effect whatsoever on unit operation. Only the user−defined dew point
adjustment setting affects operation per the following formula:
RHsetpoint =Outdoor Temp (ºF)
2+ 25 + RHuser dew point adjust-
ment
Where: RHuser dew point adjustment cannot exceed +/−15% and
RHsetpoint minimum is 15% and cannot exceed 45%.
Scroll to HUMIDITY SETTINGS; press ENTER.
HUMIDITY MODE
HUMIDIFY DEHUMIDIFY
||
Press the box below HUMIDIFY. Use up/down arrows to select DEW-
POINT; press ENTER.
HUM MODE SETTING
DEF(OFF) DEWPOINT
Use up/down arrows to select new DEW POINT ADJ setpoint (between
+15 to −15%); then press SAVE.
DEW POINT ADJ
DEFAULT (O%) −5%
NOTE − Dew point adj available only when outdoor sensor is attached.

506228−01 05/09 Page 20
Humidification (continued)
USER SETTINGS
BASIC & PRECISIONif set up by the installer settings for BASIC or
PRECISION, this adjustment controls the relative humidity (RH) be-
tween 15 and 45%.
Scroll to HUMIDITY SETTINGS; press ENTER. Press the box below
HUMIDIFY.
HUMIDITY MODE
HUMIDIFY DEHUMIDIFY
||
Use up/down arrows to change the humidity setpoint (between 15 and
45%); press SAVE.
HUM SETPOINT
DEFAULT (45%) 4O%
DEWPOINTif set up by the installer settings for dew point, this adjust-
ment (only when in heating mode) will change the humidification set-
point based on the outdoor temperature and a user−defined dew point
adjustment setting. When humidifying, if condensation forms on the
windows, the dew point should be adjusted in the range of −15 to −5%; if
the home feels dry, set dew point upward in the range of +5 to +15%.
Scroll to HUMIDITY SETTINGS; press ENTER. Press the box below
HUMIDIFY.
HUMIDITY MODE
HUMIDIFY DEHUMIDIFY
||
Use up/down arrows to change the dew point (between +15 and −15%);
press SAVE.
DEW POINT ADJ
DEFAULT (O%) −5%
NOTE − Dew point adj available only when outdoor sensor is attached.
OFFif OFF selected in installer settings for both humidify and dehu-
midify, this message appears when HUMIDITY SETTING is pressed:
HUMIDITY MODES OFF
If OFF is selected by the installer settings for HUMIDIFY but DE-
HUMIDIFY is on, the dehumidification menu appears (this setpoint ad-
just has NO effect on humidification):
DEHUM SETPOINT
DEFAULT (5O%) 45%