Lennox ComfortSense L7742U Programming And Application Manual Download

Page: 1 / 44

05/09

506228−01

*2P0509*

*P506228-01*

2009 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:

installation uses 18 GAUGE thermostat wire or larger,

thermostat wire run length DOES NOT EXCEED 300’ (91m),

load 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.

Summary of Contents for ComfortSense L7742U

Page 1: ...rogrammable 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 S i...

Page 2: ...ic 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 con...

Page 3: ... 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 se...

Page 4: ...over mode two sets of up down arrows ap pear G Informationdisplay 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 in...

Page 5: ...dehumidifying cooling or heating will alternately be displayed in the information display Equipmentoperation 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 hea...

Page 6: ...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...

Page 7: ... 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 accor...

Page 8: ...ekday programming and SAT TO SUN weekend programming C MONDAY through SUNDAY allows individual days of the week to be programmedseparately 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 repeatedlyto scroll to the desired grouping Programm...

Page 9: ...ired 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 oth...

Page 10: ...ONS 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 selec...

Page 11: ...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...

Page 12: ...JUST 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 arr...

Page 13: ...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...

Page 14: ... 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 firs...

Page 15: ...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 2n...

Page 16: ...d 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 CU...

Page 17: ...efault 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 Scrol...

Page 18: ...ted 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 be...

Page 19: ...d 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...

Page 20: ... 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...

Page 21: ...de dehumidification occurs if these conditions are met and signals are present at specific terminals S dehumidification has been enabled on installer settings and S the unit is in COOL mode and S dehumidification demand exists RH above setpoint and S cooling demand exists Y1 energized In PRECISION mode dehumidification occurs if all BASIC conditions are true except cooling demand may or may not be...

Page 22: ...DITY SETTING is pressed HUMIDITY MODES OFF If OFF is selected by the installer settings for DEHUMIDIFY but HU MIDIFY is on the humidification menu appears this setpoint adjust has NO effect on dehumidification HUM SETPOINT DEFAULT 45 4O Humiditrol Enhanced Dehumidification Accessory If a Humiditrol EDA is present in the equipment at hand then the Com fortSense Model L7742U thermostat must be confi...

Page 23: ...ler than 2ºF above heating setpoint In this case the 24 VAC is removed from the D terminal and the Y1 Y2 terminal if available becomes activated with 24VAC This will cycle the indoor variable speed motor to the dehumidification speed and cycle Y2 ON to the outdoor unit Cooling calls have priority over Humiditrol calls Humiditrol mode is allowed to overcool up to 2 F above the heating setpoint Note...

Page 24: ...ing or cooling will not raise or lower the room temperature to the set point in a given time When OFF is selected all stage delay timers are disabled This means stages are changed based on the temperature and not their timer de lays Scroll to STG DELAY TIMERS press ENTER STG DELAY TIMERS DEFAULT ON OFF DIFFERENTIAL SETTINGS The differentials below and shown in the figures 6 through 13 are defaults...

Page 25: ... 75ºF Press SAVE STG2 HP LOCK TEMP DEFAULT OFF 25 F Configuration Figure Multi stage Cooling for Heat Pump Non Heat Pump 6 Heating Non Heat Pump 1 or 2 stages 7 Heating Heat Pump with NO backup heat 7 Heating Heat Pump w electric heat 2 stage 1compr 1backup 7 Heating Heat Pump w electric heat 3 stage 2compr 1backup 8 Heating Heat Pump w electric heat 3 stage 1compr 2backup 8 Heating Heat Pump w el...

Page 26: ...l SET POINTS Figure 7 Heating Non Heat Pump or Heat Pump w o backup heat 1 or 2 stages H C Stages Locked NO H C Stages Locked YES SET POINTS 3rd stage ON 1st stage ON 2nd stage ON 3rd stage ON 1st stage ON 2nd stage ON 2nd stage OFF 3rd stage OFF 1st stage OFF 1st stage OFF 2nd stage OFF 3rd stage OFF SP 1 5 SP 1 0 SP 0 5 SP SP 0 5 SP 2 0 Stg1 Differential Stg3 Differential Stg2 Differential SP 2 ...

Page 27: ...al 1st stage OFF 2nd stage OFF 3rd stage OFF 4th stage OFF SET POINTS SP 1 5 SP 1 0 SP 0 5 SP SP 0 5 SP 2 0 Stg1 Differential Stg3 Differential Stg2 Differential SP 2 5 SP 3 0 SP 3 5 Stg1 Differential Stg3 Differential Stg2 Differential Stg4 Differential Figure 9 Heating Heat Pump w electric 4 stage 2 compressor 2 backup H C Stages Locked NO or YES 2nd stage ON 1st stage ON 2nd stage OFF 1st stage...

Page 28: ...tage ON 2nd stage ON 3rd stage ON 1st stage ON 2nd stage ON 2nd stage OFF 3rd stage OFF 1st stage OFF 1st stage OFF 2nd stage OFF 3rd stage OFF SP 1 5 SP 1 0 SP 0 5 SP SP 0 5 SP 2 0 Stg1 Differential Stg3 Differential Stg2 Differential SP 2 5 SP 3 0 SP 3 5 Stg1 Differential Stg3 Diff Stg2 Differential Figure 11 Heating dual fuel 3 stage 1 compressor 2 backup ...

Page 29: ...INTS 3rd stage ON 1st stage ON 2nd stage ON 3rd stage ON 1st stage ON 2nd stage ON 2nd stage OFF 3rd stage OFF 1st stage OFF 1st stage OFF 2nd stage OFF 3rd stage OFF SP 1 5 SP 1 0 SP 0 5 SP SP 0 5 SP 2 0 Stg1 Differential Stg3 Differential Stg2 Differential SP 2 5 SP 3 0 SP 3 5 Stg1 Differential Stg3 Differential Stg2 Differential Figure 12 Heating dual fuel 3 stage 2 compressor 1 backup ...

Page 30: ... 1st stage ON 2nd stage ON 4th stage ON 2nd stage OFF 3rd stage OFF 4th stage OFF 1st stage OFF Stg4 Differential 1st stage OFF 2nd stage OFF 3rd stage OFF 4th stage OFF SET POINTS SP 1 5 SP 1 0 SP 0 5 SP SP 0 5 SP 2 0 Stg1 Differential Stg3 Differential Stg2 Differential SP 2 5 SP 3 0 SP 3 5 Stg1 Differential Stg3 Differential Stg2 Differential Figure 13 Heating dual fuel 4 stage 2 compressor 2 b...

Page 31: ... the top set of arrows appear 1 On the home screen press the UP or DOWN arrow to adjust to the desired temperature 2 A set of arrows appears to the right of the information display use these arrows to adjust the hold period for as long as desired or if not changed this setting will hold for approximately 3 hours 3 Press SAVE 4 After saving ON next to the SCHED button flashes slowly and the informa...

Page 32: ... information display lower center of the screen NOTE For proper operation of Humiditrol EDA applications the out door sensor MUST be installed In many applications the ComfortSense Model L7742U thermostat displays the temperature sensed by the remote outdoor sensor With the heat pump system the remote outdoor sensor helps determine when to turn on the second stage of heating for optimal comfort Wh...

Page 33: ...turned off the indicator will not be activated even if the timer is expired Note that setting filter reminder to 0 OFF will not reset the timers but will deactivate the filter indicator In the case of a power interruption S lithium battery has charge the total accumulated time is main tained i e the counter does not recycle to zero S lithium battery has NO charge the due date of reminders is main ...

Page 34: ...ating set point YES YES NO NO NO NO YES ONE OR BOTH TRUE NEITHER IS TRUE Is there a cooling demand Is there a dehumidification demand DEACTIVATE ALL EQUIPMENT RUN EQUIPMENT IN NORMAL HEATING MODE RUN EQUIPMENT IN NORMAL COOLING MODE Is EITHER true outdoor temp 95ºF indoor temp 65ºF Humiditrol Comfort Adjust setting is RUN HUMIDITROL START Is there a heating demand YES Figure 15 ComfortSense Model ...

Page 35: ...YES HP stage demand Stg1 Stg2 Energize Y1 B G and start upstage timer Energize Y1 Y2 B G and start upstage timer Indoor heat demand NO YES Upstage timer expired NO 2nd stage demand YES YES ODT LBSP 3 NO YES NO Indoor heat demand NO YES NO 3rd stage demand YES YES ODT LBSP 3 NO YES NO De energize Y1 or Y1 Y2 and G 2nd stg HP Y2 or Gas W1 A ODT HBSP 3 or if HBSP is OFF W1 Y2 De energize W1 and W2 HE...

Page 36: ...UNIT SEE SPECIFIC MODEL FOR ACTUAL TERMINAL LAYOUT TYPICAL 2 STAGE OUTDOOR UNIT PUR OUTDOOR SENSOR X2658 BLK Y1 Y2 JUMPER OR ON BOARD CLIPPABLE LINK IN FOR SINGLE STAGE COOLING REMOVED FOR 2 STAGE COOLING RED BLK PUR EDA UNIT FAN RELAY REMOVE Y1 TO DS OR R TO DS JUMPER IN INDOOR UNIT FOR HUMIDITROL APPLICATION NOT REQUIRED FOR APPLICATIONS WITHOUT LSOM NOT REQUIRED FOR SINGLE STAGE NOTE FAN RELAY ...

Page 37: ...Page 37 ComfortSenset Model L7742U Touch Screen 7 Day Programmable Thermostat Figure 18 CBX40UHV Wiring Diagrams ...

Page 38: ...506228 01 05 09 Page 38 Figure 19 Thermostat Wiring Diagrams ...

Page 39: ...art working again Need to re duce temperature in space Local Temp Sensor error local temp sensor reads out of range 40F to 158F TEMP SENSOR ERROR CALL FOR SERVICE Contact Info Screen Indoor temp is displayed as EE on the home screen This will STOP all temperature related op eration User call dealer number from con tact information screen and request thermostat replacement OR If the sensor reads ba...

Page 40: ...n the display from USER SETTINGS this error is displayed again If the outdoor sensor reads a value out of its normal range User can call the dealer to replace outdoor sensor Outdoor Sensor error with Dew point control enable outdoor sensor reads out of range 50F to 180F NO OUTDOOR SENSOR REMIND SERVICE See REMIND SERVICE notes No Dew point control or Humidity operation is run D terminal stays acti...

Page 41: ...90 Normal opera tion 90 93 Stat may detect error 93 Stat will detect error HUM SENSOR ERROR REMIND SERVICE See REMIND SERVICE notes All the humidity operation will stop and the reading for humidity will not be valid This message indicates something seriously wrong with the thermostat The display of Indoor Humidity from HOME will be turned OFF If user turns it on again the error is dis played Repla...

Page 42: ... that message will be displayed first Heating only when sys tem is in Heat Call HEATING Date Time Displayed on first line Second line has Date Time info on it When call is ended OR when high er priority reminder error occurs Cooling only when sys tem is in cool call COOLING Date Time Displayed on first line Second line has Date Time info on it When call is ended OR when high er priority reminder e...

Page 43: ...AM Message is displayed on the screen and system has a tempo rary hold on temperature Message will disappear when user hits SCHED or if higher priority Er ror Reminder occurs Compressor Protection timer 5min is running WAIT Message is displayed on the screen whenever compressor protection is running AND cooling heating demand exists Message will disappear when com pressor protection run expires OR...

Page 44: ...W1 W2 W1 W2 W1 W2 W1 W2 Cool Stages 1 1 1 2 2 2 1 1 1 2 2 2 1 1 1 2 2 2 1st Cool Stage Y1 Y1 Y1 Y1 Y1 Y1 Y1 Y1 Y1 Y1 Y1 Y1 Y1 Y1 Y1 Y1 Y1 Y1 2nd Cool Stage Y1 Y2 Y1 Y2 Y1 Y2 Y1 Y2 Y1 Y2 Y1 Y2 Y1 Y2 Y1 Y2 Y1 Y2 Indoor Heat Stgs X X X X X X X X X X X X Outdoor Sensor X X X X X X X X X X X X X X X X X X Residual Cool X X X X X X X X X X X X X X X X X X Low Balance Pt X X X X X X X X High Balance Pt X...

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