Lennox ComfortSense L7742U Programming Guide

09/08 506180−01
*2P0908* *P506180-01*
E2008 Lennox Industries Inc.
Dallas, Texas, USA
COOLING
TUE OCT 23 1:15PM
IMPORTANT
Read this manual before programming this thermo-
stat.
Use this thermostat only as described in this manual.
Shipping and Packing List
1 − ComfortSenset Model L7742U touch screen, 7−day
programmable 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
CAUTION
This is a 24VAC low−voltage thermostat. Do not
install on voltages 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 thermostat and void the war-
ranty.
IMPORTANT
In commercial applications, the ComfortSenset
Model L7742U thermostat can only be used with ap-
proved split-system matches, and those which meet
the following installation criteria:
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, con-
sult Application Note H−04−5.
PROGRAMMING AND
APPLICATION GUIDE
(SERVICEMAN’S MANUAL)
ComfortSenset 7000 Series
Model L7742U Touch Screen Programmable
Thermostat
CONTROLS
506180−01
09/08
Table of Contents
ComfortSenset Model L7742U Thermostat 2. . . . . .
Features 2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Display Fields & Touch Screen Points 2. . . . . . . . . . . .
Home ScreenCurrent Conditions & Temp. Settings 3
Controlling the Heat/Cool Modes of Operation 4. . . . .
Controlling the Fan Operation 5. . . . . . . . . . . . . . . . . . .
Schedule ScreenProgramming 6. . . . . . . . . . . . . . . .
Options screenReminders & User Settings 7. . . . . .
Options screenInstaller Settings 8. . . . . . . . . . . . . . .
Resetting Program to Factory Conditions 10. . . . . . . . .
EPA ENERGY STAR
®
Recommended Setpoints 10. .
Humidification 10. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Dehumidification 11. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Humiditrol
®
Enhanced Dehum. Accessory (EDA) 12. .
Stage Delay and Differential Settings 13. . . . . . . . . . . . .
Temporary Temp. ChangePause the Schedule 16. .
Remote Outdoor Sensor 16. . . . . . . . . . . . . . . . . . . . . . .
Memory Protection 17. . . . . . . . . . . . . . . . . . . . . . . . . . . .
Date Code & Serial Number 17. . . . . . . . . . . . . . . . . . . .
Appendix A. Flow Diagrams & Wiring Diagrams 18. . .
Appendix A. Diagnostic Info. & Hidden Menu Tables 20
NOTE − This thermostat is equipped with automatic com-
pressor 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 being dam-
aged.
WARNING
Always turn off power at the main power source by
switching the circuit breaker to the OFF position be-
fore installing or removing this thermostat.
All wiring must conform to local and national build-
ing and electrical codes and ordinances.
Do not switch system to cool if the outdoor tempera-
ture is below 45°F (7°C). This can damage the cool-
ing system.
Litho U.S.A.

Lennox ComfortSense L7742U Specifications

General

Brand	Lennox
Model	ComfortSense L7742U
Category	Thermostat
Language	English