02/08
506072−01
*2P0208*
*P506072-01*
E
2008 Lennox Industries Inc.
Dallas, Texas, USA
RETAIN THESE INSTRUCTIONS
FOR FUTURE REFERENCE
L3711C 7−Day Programmable Thermostat
The Lennox ComfortSense
t
3000 Series model L3711C
7-day programmable electronic thermostat provides
excellent temperature control and has a large,
easy-to-read display. This product includes a
programmable filter change reminder, an equipment
maintenance reminder, and a system check indicator to
notify the user when the equipment requires service.
Thermostat model L3711C is suitable for non−heat pump,
single-stage heat/single-stage cool applications with either
gas or electric furnace. Also, the thermostat provides auto-
changeover capability.
OPERATION MANUAL
ComfortSense
t
3000 Series
Model No. L3711C 7-Day
Programmable Thermostat
CONTROLS
506072−01
02/08
Supersedes 505,067M
Table of Contents
7−Day Programmable Thermostats
. . . . . . . . . . . . . . .
General
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Introduction
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Initial Thermostat Power-up
. . . . . . . . . . . . . . . . . . . . .
Buttons, Backlight, Timers & Settings
. . . . . . . . . . . .
DAY/TIME − Set Day and Time
. . . . . . . . . . . . . . . . . .
HEAT − Heat Mode
. . . . . . . . . . . . . . . . . . . . . . . . . . . .
COOL − Cool Mode
. . . . . . . . . . . . . . . . . . . . . . . . . . . .
AUTO − Using the Autochangeover Mode
. . . . . . . . .
HOLD − Temperature Hold Mode
. . . . . . . . . . . . . . . .
PROG − Thermostat Programming
. . . . . . . . . . . . . . .
COPY − Copy a Program
. . . . . . . . . . . . . . . . . . . . . . .
FAN − Controlling Fan Operation
. . . . . . . . . . . . . . . . .
Displaying Outside Temperature
. . . . . . . . . . . . . . . . .
SETTINGS − Filter /Maintenance Reminder
. . . . . . .
Service Indicator
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Thermostat RESET
. . . . . . . . . . . . . . . . . . . . . . . . . . . .
Removing/Installing Thermostat
. . . . . . . . . . . . . . . . .
Default Thermostat Settings
. . . . . . . . . . . . . . . . . . . .
Thermostat Output Table
. . . . . . . . . . . . . . . . . . . . . . .
Technical Specifications
. . . . . . . . . . . . . . . . . . . . . . . .
General
These instructions are intended as a general guide and do
not supersede local codes in any way. Consult authorities
having jurisdiction before installation.
Check equipment for shipping damage. If you find any
damage, immediately contact the last carrier.
Introduction
This document describes the operation of Lennox model
L3711C thermostat. Refer to the installation manual for in-
structions regarding installation and wiring of the thermo-
stat.
Initial Thermostat Power-up
When power is initially applied to the thermostat, the dis-
play will appear as shown in figure 1.
HEAT SETPOINT
COOL
OFF
AUTO
EMG.
HEAT
I8:88
i88
AM
PM
OUTROOM
MO TU WE TH FR SA SU
COOL SETPOINT
FILTER
MAINTENANCE
Hi
Lo
FAN ON
AUTO
°
°
°
SERVICE
Copy tofrom
PROG
A
B
C
D
HOLD
88
88
Figure 1. Initial Power−Up Display
All display segments are momentarily activated. This oc-
curs as a normal part of thermostat initialization.
Litho U.S.A.
