Page 3
ComfortSense
t
Model L7742U Touch Screen 7−Day Programmable Thermostat
ComfortSense
®
Model L7742U Thermostat (Catalog No. Y2081)
Description
The ComfortSense
®
Model L7742U thermostat is an electronic 7−day
universal multi-stage programmable touch screen thermostat. It also
offers enhanced capabilities which include:
S
humidification measurement and control,
S
dew point adjustment control,
S
dehumidification measurement and control,
S
Humiditrol
®
Enhanced Dehumidification Accessory (EDA) capa-
bility,
S
equipment maintenance reminders,
S
worry−free memory storage feature,
S
menu−driven display.
This thermostat supports heat pump units or non−heat pump units, with
up to 4 stages of heating (dual fuel units) and 2 stages of cooling.
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
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.
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 sensor enables optimal heating equip-
ment 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 can be dis-
played in the information display area (see figure 2).
NOTE − For proper operation of Humiditrol
®
EDA applications, the out-
door sensor (X2658) MUST be installed.
L" Input
L" input from the equipment is used to notify the user of an outdoor
equipment fault by displaying HVAC ERROR DETECTED" when one
of the following conditions exist:
S
L" terminal is activated with 24VAC and Y1 has been activated
for 5 minutes (units without LSOM, but which use Service Light
Monitor Kit), OR,
S
LSOM error signal is detected on L" input and Y1 has been acti-
vated for 5 minutes.
NOTE − The L input is used for diagnostic information purposes only, it
is not intended to provide equipment protection.
