Service Reminders; Memory Protection - Lennox L7742U Owner's Manual

Optional Remote Outdoor Sensor
The outdoor sensor (X2658) may be required, especially when using
Humiditrol® EDA applications. In addition to measuring and displaying
outdoor temperature, the outdoor sensor provides dew point adjust-
ment and control for all models. If used with this thermostat, the sensor
enables optimal heating equipment operation via programmable bal-
ance points. The screen will display NO OUTDOOR SENSOR until the
outdoor sensor is installed, the feature is turned on in the installer setup,
and if the user turns it on in the DISPLAY INFO option in user setup. The
outdoor temperature is displayed in the information display (lower cen-
ter of the screen).
NOTE − For proper operation of Humiditrol® EDA applications, the
outdoor sensor MUST be installed.
In many applications, the ComfortSenset Model L7742U thermostat
will display 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.
When the outdoor sensor is connected, the temperature displays in the
information display area (below the indoor temperature display).

Memory Protection

The thermostat stores all the information concerning its programming
(state, mode, program information, last temperature measured) in a
nonvolatile memory.
This function avoids the loss of the state of the thermostat when a pow-
er−down occurs. The only thing that might be lost is the clock, however,
a lithium battery will remember clock information for as long as it has
charge (approximately 30 days). When power down occurs (due to a
power outage) the thermostat is able to switch off all relays. The O and
B relay will maintain their last state.
506062−01 06/08

Service Reminders

The user may turn on and turn off the following service reminders (all of
which default to OFF) in either chronological time and/or run time and
may be reset (to default) or delayed (snooze) at any time:
Replace Media Filter
Routine Sys (System) Check−up
Replace Hum (Humidifier) Pad
Replace UV Lamp
Replace Metal Insert for Pure Air
NOTE − When chronological time is selected, the timer runs based on
the calendar. When time is selected in run time, the timer runs based
on the time the specific output is ON (e.g. Fan output for Media Filter).
When the reminder time (either calendar time or run time) has elapsed,
the system displays a screen from which the user can either RESET or
DELAY the reminder.
The user can reset the timer either before is has expired (i.e. reminder is
set to 6 months and user decides to reset it to 6 months or change it to
different value at the end of 4th month) or when the time has expired and
a reminder messages has been displayed.
When a reminder is 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-
tained.
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