Lennox L7742U Programming And Application Manual
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Lennox L7742U Programming And Application Manual

Comfortsense 7000 series
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See also: Programming Manual , Programming and Application Manual
Enlarged version
E2008 Lennox Industries Inc.
Dallas, Texas, USA
TUE OCT 23 1:15PM
Shipping and Packing List
1 −
ComfortSenset 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
06/08
*2P0608*
COOLING
PROGRAMMING AND
APPLICATION GUIDE
ComfortSenset 7000 Series
Model L7742U Touch Screen Programmable Thermostat
CONTROLS
506061−01
06/08
Supersedes 05/08
IMPORTANT
In commercial applications, the ComfortSenset Model L7742U
thermostat can only be used with approved split-system
matches, and those which meet the following installation crite-
ria:
S installation uses 18 GAUGE thermostat wire or larger,
S thermostat wire run length DOES NOT EXCEED 300' (91m),
S load from any thermostat connection is LESS THAN 1 AMP.
®
If used with Harmony II
Zone Control System, consult Applica-
tion Note H−04−5.
Litho U.S.A.
506061−01
*P506061-01*

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  • Page 1 06/08 Supersedes 05/08 COOLING TUE OCT 23 1:15PM IMPORTANT In commercial applications, the ComfortSenset Model L7742U thermostat can only be used with approved split-system matches, and those which meet the following installation crite- ria: Shipping and Packing List S installation uses 18 GAUGE thermostat wire or larger, 1 −...

  • Page 2: Table Of Contents

    Table of Contents WARNING ComfortSenset Model L7742U Thermostat ... . . Always turn off power at the main power source by switching Features ......... .

  • Page 3: Comfortsenset Model L7742U Thermostat

    If used with this thermostat, the sensor enables optimal heating equipment operation via programmable balance points. Description The ComfortSenset Model L7742U thermostat is an electronic 7−day NOTE − The outdoor sensor uses standard thermostat wiring; it universal multi-stage programmable touch screen thermostat. It also may be wired using two wires of a multi−wire cable.

  • Page 4: Display Fields & Touch Screen Points

    H Displays different information depending on the tab selected: HOME tab: displays outdoor temperature (if outdoor sen- sor Lennox P/N X2658 is installed), indoor relative humid- ity (RH), which mode is calling, hold settings information, service reminders. SCHEDULE tab: displays the event being programmed;...

  • Page 5: Home Screen Current Conditions & Temperature Settings

    (outdoor sensor is required when humidity controlling fea- grammable schedule, or in a non−programmable mode using the tures are implemented). Other system operational information, such as SCHED box. ComfortSenset Model L7742U Touch Screen 7−Day Programmable Thermostat Page 5...

  • Page 6: Controlling The Heat/Cool Modes Of Operation

    When the faults, errors, and service information displays appear, action Controlling the Heat/Cool Modes of Operation boxes will appear under the second line entries, REMIND, CLEAR, SERVICE, or RESET. Press the box to perform the action. Press the screen anywhere − the first press turns on the backlight. While in the HOME screen, press MODE field;...

  • Page 7: Controlling The Fan Operation

    (FAN ON or FAN CIRC). manual user inputs. ComfortSenset Model L7742U Touch Screen 7−Day Programmable Thermostat Page 7...

  • Page 8: Schedule Screen Programming

    Schedule Screen Programming Press the screen anywhere − the first press turns on the backlight. Programming may be performed in groups of days (5/2 or all 7) or indi- vidual days, as follows: Press the SCHEDULE tab along the top of the screen. The display MON TO SUN −...
  • Page 9 Repeat steps 3 through 8 for the remaining days, if necessary. Press SAVE when all events and The changes are made and the days are programmed as desired schedule screen reappears. ComfortSenset Model L7742U Touch Screen 7−Day Programmable Thermostat Page 9...

  • Page 10: Options Screen Reminders & User Settings

    Options screen Reminders & User Settings CLEAN button Reminders [ OPTIONS TAB > REMINDERS > [ENTER] Set timers from 1 to 24 months in either calendar time or system run When you select the OPTIONS tab, two buttons appear near the bot- time.
  • Page 11 For INDOOR RH, use arrows to select ON or OFF; then press SAVE. 25% (15 minutes fan run time per hour) INDOOR RH 35% (21 minutes fan run time per hour) DEFAULT(OFF) 45% (27 minutes fan run time per hour). ComfortSenset Model L7742U Touch Screen 7−Day Programmable Thermostat Page 11...
  • Page 12 Options screen Reminders & User Settings (continued) COOLING LIMIT default is 45º; to change to any degree between NOTE − If the user settings security code is forgotten or misplaced for 45ºF and 99ºF, scroll to COOLING LIMIT; press ENTER. Use arrows to some reason, the universal code 864"...

  • Page 13: Options Screen Installer Settings

    0, 30, 60, 90, and 120; press SAVE. RESIDUAL COOL For HEAT PUMP, use arrows to select backup heat: NO BACKUP DEFAULT(OS) HEAT, DUAL FUEL (GAS/OIL), or ELECTRIC; then press SAVE. ComfortSenset Model L7742U Touch Screen 7−Day Programmable Thermostat Page 13...
  • Page 14 Options screen Installer Settings (continued) LOW BALANCE POINT default 25°F (heat pump only, and if outdoor SSR STG2 LOCK OUT default is 20 minutes. Second stage opera- sensor installed). If outdoor temperature is below programmed Low tion is not allowed until the last 20 minutes before the programmed start Balance Point, compressor heating is not allowed.

  • Page 15: Resetting Program To Factory Conditions

    CUSTOM REMINDER 1 rows to select OFF. Press SAVE. CLEAN OUTDOOR UNIT DAYLIGHT SAVING TIME RESET SETTINGS To reset the ComfortSenset Model L7742U DEFAULT(ON) thermostat to factory defaults, scroll to RESET SETTINGS. HUMIDITY SETTING See separate sections − Humidification IMPORTANT (Page 18) and Dehumidification (Page 20).

  • Page 16: Epa Energy Star ® Recommended Setpoints

    Options screen Installer Settings (continued) ® Hardware reset a hardware reset may be performed if necessary. ENERGY STAR DEFAULT EPA ENERGY STAR recommended This procedure requires separating the thermostat from the base and setpoints for heating and cooling can help the household save energy. shorting across points A and B as shown in figure 6.
  • Page 17 D ON D OFF O ON (B OFF) All HVAC components can be tested to confirm the signals between B ON (O OFF) thermostat and unit are being sent and received. ComfortSenset Model L7742U Touch Screen 7−Day Programmable Thermostat Page 17...

  • Page 18: Humidification

    Humidification INSTALLER SETTINGS Use up/down arrows to select BASIC or PRECISION; press ENTER. HUM MODE SETTING DEF(OFF) PRECISION Humidification (adding moisture to air) is provided only when the ther- mostat is in heat mode. The humidification signal (H terminal) to the hu- Default setting is 45% RH.
  • Page 19 −15 to DEHUM SETPOINT −5%; if the home feels dry, set dewpoint upward in the range of +5 to DEFAULT (5O%) +15%. ComfortSenset Model L7742U Touch Screen 7−Day Programmable Thermostat Page 19...

  • Page 20: Dehumidification

    Dehumidification INSTALLER SETTINGS HUMIDITROL mode requires: outdoor sensor must be installed and setup Dehumidification (removing moisture from air) can occur only when the dehumidification has been enabled on installer settings, and thermostat is in cool mode. When a dehumidification demand is pres- the unit is in COOL mode, (or if in AUTO, there has been at least ent, a dehumidification signal (0VAC −...

  • Page 21: Humiditrol ® Enhanced Dehumidification Accessory (Eda)

    NO effect on dehumidification): Check the HUMIDITY SETTINGS in user settings to confirm that the HUM SETPOINT user has control of the dehumidification setting. DEFAULT (45%) The ComfortSenset Model L7742U thermostat is now configured to ® Humiditrol Enhanced Dehumidification Acces- ®...
  • Page 22 Dehumidification (continued) ComfortSenset Model L7742U thermostat operation Y2" terminal (if available) becomes activated with 24VAC. This will with Humiditrol enabled cycle the indoor variable speed motor to the dehumidification speed and cycle Y2 ON" to the outdoor unit. Cooling calls have priority over ®...

  • Page 23: Stage Delay And Differential Settings

    Scroll to STG 2 DELAY (or 3 or 4); press ENTER. Select the desired lays. Scroll to STG DELAY TIMERS; press ENTER. delay. Press SAVE. STG DELAY TIMERS STG 2 DELAY DEFAULT (ON) DEFAULT(2OMIN) 5MIN ComfortSenset Model L7742U Touch Screen 7−Day Programmable Thermostat Page 23...
  • Page 24 Stage Delay & Differential Settings (installer settings) (continued) H/C STGS LOCKED IN default NO (heat/cool stages are turned off Configuration Figure separately). If changed to YES, heat/cool stages are turned off together Multi−stage Cooling for Heat Pump/Non−Heat Pump (see figures 7 through 14). Scroll to H/C STGS LOCKED IN; press EN- TER.
  • Page 25 SP −1.5 SP −1.0 SP −0.5 SP +0.5 POINTS: Figure 9. Heating − Heat Pump w/electric − 3 stage (2 compressor / 1 backup OR 1 compressor / 2 backup) ComfortSenset Model L7742U Touch Screen 7−Day Programmable Thermostat Page 25...
  • Page 26 Stage Delay & Differential Settings (installer settings) (continued) 1st stage 1st stage Stages Stg1 Differential Locked = 2nd stage 2nd stage Stg2 Differential 3rd stage 3rd stage Stg3 Differential 4th stage 4th stage Stg4 Differential 1st stage 1st stage Stages Stg1 Differential Locked = 2nd stage...
  • Page 27 SP −3.5 SP −3.0 SP −2.5 SP −2.0 SP −1.5 SP −1.0 SP −0.5 SP +0.5 POINTS: Figure 13. Heating − dual fuel − 3 stage (2 compressor / 1 backup) ComfortSenset Model L7742U Touch Screen 7−Day Programmable Thermostat Page 27...
  • Page 28 Stage Delay & Differential Settings (installer settings) (continued) 1st stage 1st stage Stages Stg1 Differential Locked = 2nd stage 2nd stage Stg2 Differential 3rd stage 3rd stage Stg3 Differential 4th stage 4th stage Stg4 Differential 1st stage 1st stage Stages Stg1 Differential Locked = 2nd stage...

  • Page 29: Temporary Temperature Change Pause The Schedule

    HOLD SETTING UNTIL 10:49AM OCT 10 display alternates between the following: HOLD SETTING UNTIL WKD MMM DD HH:MMMM PRESS SCHED TO RESUME PROGRAM Figure 15. Setting a Hold on the Schedule ComfortSenset Model L7742U Touch Screen 7−Day Programmable Thermostat Page 29...

  • Page 30: Remote Outdoor Sensor

    MUST be installed. nonvolatile memory. In many applications, the ComfortSenset Model L7742U thermostat This function avoids the loss of the state of the thermostat when a pow- will display the temperature sensed by the remote outdoor sensor. With er−down occurs.

  • Page 31: Date Code & Serial Number

    A label on the back of the thermostat is visible through an opening in the When the reminder time (either calendar time or run time) has elapsed, back of baseplate. This identifies the Lennox Catalog Number, Part the system displays a screen from which the user can either RESET or Number and Serial Number.

  • Page 32: Appendix A. Flow Diagrams & Wiring Diagrams

    EITHER true: temp. > 2ºF below ONE OR NEITHER outdoor temp. > 95ºF; cooling set point BOTH TRUE indoor temp. < 65ºF IS TRUE ® Figure 16. ComfortSenset Model L7742U Thermostat Operation with Humiditrol EDA Enabled 506061−01 06/08 Page 32...
  • Page 33 < HBSP − 3 or (if HBSP is OFF) Indoor heat demand Upstage 3rd stage Indoor heat < LBSP − 3 timer expired demand demand De−energize Y1 or Y1&Y2, and G ComfortSenset Model L7742U Touch Screen 7−Day Programmable Thermostat Page 33...
  • Page 34 Thermostat wiring connections with various units, including dual fuel, zone control, and applications that include the Humidi- ® trol Enhanced Dehumidification Accessory (EDA). See figures 18 and 19. OUTDOOR SENSOR (X2658) EDA UNIT RELAY Y1 Y2 JUMPER − IN FOR L7742U SINGLE− STAGE COOLING; OUTDOOR INDOOR THERMOSTAT REMOVED FOR 2−STAGE UNIT UNIT COOLING NOTES −...
  • Page 35 REQUIRED WHEN USING D TO DS TERMINALS WITH TEMPERING, SET W2 TO CB(X)27 UNITS. TIMED ON. NOTE: NOT ALL UN- USED TERMINALS ARE SHOWN ON T’STAT DIAGRAMS. Figure 19. Thermostat Wiring Diagrams ComfortSenset Model L7742U Touch Screen 7−Day Programmable Thermostat Page 35...

  • Page 36: Appendix A. Diagnostic Information & Hidden Menu Tables

    Appendix B. Diagnostic Information and Hidden Menu Tables Diagnostic Information Table Message Action to Clear / Recovery Type Condition Condition Display Text (Screen1) Display Text (Screen2) Priority System Action Error AC power loss with *No message Thermostat can detect AC power loss and Stat. will operate When AC power recovers stat.
  • Page 37 REPLACE UV LAMP See REMIND/RESET notes 2−Mod- Displayed on both lines on HOME. User either Hit RESET or RE- REMIND RESET erate MINDER button on HOME table continued on next page ComfortSenset Model L7742U Touch Screen 7−Day Programmable Thermostat Page 37...
  • Page 38 Message Action to Clear / Recovery Type Condition Condition Display Text (Screen1) Display Text (Screen2) Priority System Action Reminder Humidity Pad REPLACE HUM PAD See REMIND/RESET notes 2−Mod- Displayed on both lines on HOME. User either Hit RESET or RE- REMIND RESET erate...
  • Page 39 AUTO to ON or CIRC On home CIRC in the current pe- 2 − User changes FAN mode in the riod of schedule & schedule from CIRC to something (system is not heating else or cooling) ComfortSenset Model L7742U Touch Screen 7−Day Programmable Thermostat Page 39...
  • Page 40 Hidden Menu Table Setup HEAT PUMP NON HEAT PUMP Backup/ Indoor Gas/ Gas/Oil None Gas/ Gas/Oil None Elec Elec None Elec Elec None G/O or G/O or None G/O or G/O or None Heat Elec Elec Elec Elec Comp. Stages Indoor Heat Stgs Total Heat Stgs 1st Heat Stage...

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