Lennox l7742u User Manual
HOMEOWNER’S MANUAL
E2009 Lennox Industries Inc.
Dallas, Texas, USA
ComfortSense® 7000 Series
Model L7742U Touch Screen Programmable Thermostat
CONTROLS
506229−01
05/09
Supersedes 04/09
Litho U.S.A.
Table of Contents
ComfortSense® 7000 Series Model L7742U Thermostat 2. . .
Display Fields & Touch Screen Points 3. . . . . . . . . . . . . . . . . .
Home ScreenCurrent Conditions & Temperature Settings 4
Controlling the Heat/Cool Modes of Operation 5. . . . . . . . . . .
Controlling the Fan Operation 6. . . . . . . . . . . . . . . . . . . . . . . . .
Controlling the Schedule 6. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Schedule ScreenProgramming 8. . . . . . . . . . . . . . . . . . . . . .
S Tabbed user interface with
touch screen interaction
S Soft blue backlighted screen
with adjustable brightness
S Equipment maintenance
reminders
05/09 506229−01
S Humidification measurement
and control
S Programmable or
non−programmable options
S Automatically changes
between heating cooling
Options screenReminders & User Settings 9. . . . . . . . . . . .
Humidification 12. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Dehumidification 13. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Humiditrol® EDA Accessory 13. . . . . . . . . . . . . . . . . . . . . . . . . .
Temporary Temperature ChangePause the Schedule 14. . .
Remote Outdoor Sensor 15. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Memory Protection 15. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
*2P0509* *P506229-01*
ComfortSense® 7000 Series Model L7742U Thermostat
The ComfortSense® 7000 Series Model L7742U thermostat is an electronic 7−day, universal, multi−stage, programmable, touch screen thermostat. It also offers enhanced capabilities including humidification /
dehumidification / dewpoint measurement and control, Humiditrol
EDA (Enhanced Dehumidification Accessory) control, and equipment
maintenance reminders.
S Large, clear display with soft blue backlight shows the current and
set temperature, day/date/time, indoor relative humidity and outdoor temperature (if optional outdoor sensor is used).
S Dehumidification measurement and control
S Humiditrol® EDA capability
S Dew point adjustment control
S Menu−driven programming guides user through the scheduling
process showing only necessary information on each screen.
S Ergonomic design.
S Smooth Setback Recovery starts system early to achieve set-
point at start of program period.
S Compressor short−cycle protection (5 minutes).
S Real−time clock keeps time during power failures and automati-
®
cally adjusts for daylight savings time and leap year.
S Maintenance reminders let user know when to service or replace
filters, humidifier pads, ultraviolet lamps, plus two user or installer
defined custom reminders.
S Program Hold options allow user to override the program sched-
ule as desired by time and date.
S Select individual days or groups of days to set programming.
S Programmable fan offers increased performance when combined
with whole home indoor air quality products.
S Outdoor temperature display (with optional outdoor sensor)
shows current outdoor temperature.
Your installer has set up your thermostat based on the type of heating
and cooling system and accessories that your thermostat connects to.
This booklet details user settings available to you that will give you as
much functionality and control as you want.
506229−01 05/09
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Touch Screen Display
B
C
A
E
D
F
E
G
H
I
Figure 1. Touchscreen 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.
D Displays room temperature.
E Displays the current operation SET AT point(s). If MODE is set to
AUTO (autochangeover), both HEAT and COOL setpoints are
displayed.
F Up/down arrows used for adjusting temperature up or down; if in
AUTO (autochangeover) mode, two sets of up/down arrows appear.
G Information display area, displays different information depending
on the tab selected:
D HOME tab: displays outdoor temperature (if outdoor sen-
sor X2658 is installed), indoor relative humidity (RH),
which mode is calling, hold settings information, service
reminders.
D SCHEDULE tab: displays the event being programmed;
D OPTIONS tab: displays a scrolling list of installer- and
user−adjustable parameters, including filter and service
reminder periods, etc.
H Schedule time adjustment, User/Installer Settings up/down ar-
rows:
D HOME screen: not visible except when executing a HOLD
SETTING)
D SCHEDULE and OPTION screens: used to adjust sched-
ule and option settings.
I Dynamic 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.
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ComfortSenset Model L7742U Touch Screen 7−Day Programmable Thermostat
Home ScreenCurrent Conditions & Temperature Settings
The HOME screen (figure 2) displays indoor temperature and outdoor
temperature if the outdoor sensor is installed. Other system operational
information, such as indoor relative humidity (if turned on in user settings), 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 operation 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.
COOLING
TUE OCT 23 1:15PM
Figure 2. Home Screen
INFORMATION
DISPLAY AREA
The user can also decide whether to operate the unit per the programmable schedule, or in a non−programmable mode using the SCHED
box.
506229−01 05/09
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Controlling the 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 modesAUTO, 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 figure 3) will display one or several operational messages (listed in the
table below). If the outdoor sensor is connected, and is turned on in both
installer and user settings, outdoor temperature will be included in the
displays. The table below summarizes the information messages.
Information Display Area table
Faults, Errors, and Service Information Operating Information
TEMP SENSOR ERROR, MEMORY ERROR
CALL FOR SERVICE
NO OUTDOOR SENSOR
CALL DEALER INFO
REPLACE: MEDIA FILTER; UV LAMP; HUM PAD; METAL INSERT
REMIND RESET
ROUTINE SYS CHECK−UP
REMIND RESET
NO OUTDOOR SENSOR, HUM SENSOR ERROR, HVAC ERROR DETECTED
REMIND SERVICE
DEALER INFORMATION (Edited to show dealer contact information [2 lines])
Top line: fault/error
Bot. line: action
Top line: fault/error
Bot. line: action
Top line: serv. req’d
Bot. line: action
Top line: serv. req’d
Bot. line: action
Top line: fault/error
Bot. line: action
Contact
Installing Dealer
When the faults, errors, and service information displays appear, dynamic keys will appear under the second line entries, REMIND,
CLEAR, SERVICE, or RESET. Press the box to perform the action.
Figure 3. Selecting Mode of Operation
SET DATE/TIME
Default DATE/TIME (MON JAN 1 12:00 PM)
HEATING, COOLING, HUMIDIFYING, DEHUMIDIFYING,
SYSTEM OFF, OUTDOOR TEMP xxF, INDOOR RH xx%,
MON SEP 24 3:OO PM
SCHEDULE ON, SCHEDULE OFF, WAIT, FAN ON, FAN CIRC
MON SEP 24 3:OO PM
HOLD SETTING UNTIL PRESS SCHED TO
MON SEP 24 3:OO PM RESUME PROGRAM
INFORMATION DISPLAY AREA
[First time start up msg]
Top line: operation msgs
Bottom line: date & time
Top line: operation msgs
Bottom line: date & time
[Alternating msgs during
a held schedule]
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ComfortSenset Model L7742U Touch Screen 7−Day Programmable Thermostat
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