Comfortsenset Model L7742U Thermostat; Features - Lennox L7742U Programming And Application Manual

ComfortSenset Model L7742U Thermostat

Description
The ComfortSenset Model L7742U thermostat is an electronic 7−day
universal multi-stage programmable touch screen thermostat. It also
offers enhanced capabilities which include humidification measure-
ment and control, dew point adjustment control, dehumidification mea-
surement and control, Humiditrol
sory (EDA) capability, and equipment maintenance reminders. The
24VAC thermostat also features worry−free memory storage and a
menu−driven display. This document supports heat pumps or non−heat
pump units, with up to 4 stage heat / 2 stage cool heat pump (2 stages of
heat pump heating and 2 stages of auxiliary backup heat are provided.
Also, 2 stages of emergency heat are provided).
An optional outdoor temperature sensor (X2658) is required in applica-
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tions with Humiditrol EDA.
These instructions are intended as a general guide and do not super-
sede local codes in any way. Consult authorities having jurisdiction be-
fore installation.
Check equipment for shipping damage. If you find any damage, imme-
diately contact the last carrier.
Dimensions
Screen dimensions: 3−7/16" (87 mm) width x 2−9/16" (65 mm) height
Case dimensions: 5−7/8" (149 mm) width x 4−9/16" (116 mm) height x
1−1/4" (31mm) depth

Features

Outdoor Temperature Sensor (optional)
The outdoor sensor may be required, especially when using Humidi-
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trol EDA applications. In addition to measuring and displaying outdoor
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Enhanced Dehumidification Acces-
temperature, the outdoor sensor provides dew point adjustment and
control for all models. If used with this thermostat, the sensor enables
optimal heating equipment operation via programmable balance points.
NOTE − The outdoor sensor uses standard thermostat wiring; it
may be wired using two wires of a multi−wire cable.
When the outdoor sensor is connected, the temperature is displayed in
the information display area (see figure 2).
NOTE − For proper operation of Humiditrol
door sensor (X2658) MUST be installed.
L" Input
L" input from the equipment is used to notify the user of an equipment
fault by displaying HVAC ERROR DETECTED" when one of the fol-
lowing conditions exist:
S
L" terminal is activated with 24VAC and Y1 has been activated
for 5 minutes, OR,
S
LSOM error signal is detected on L" input and Y1 has been acti-
vated for 5 minutes.
NOTE − If system is in battery mode, the L terminal is not functional. The
L input is used for diagnostic information purposes only, it is not in-
tended to provide equipment protection.
Compressor Short Cycle Protection
A 5−minute compressor short cycle protection timer begins when a
compressor output is de−energized. Also, if a power loss occurs, the
system will go into compressor protection mode and display WAIT in
the display if there is a cooling or compressor heating call.
ComfortSenset Model L7742U Touch Screen 7−Day Programmable Thermostat
Page 3
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EDA applications, the out-