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ComfortSense
t
Model L7742U Touch Screen 7−Day Programmable Thermostat
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
PureAir
t
Maintenance
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 it 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 message 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.
Unit Part (Catalog) & Serial Numbers
A label on the back of the thermostat is visible through an opening in the
back of baseplate. This identifies the Lennox Catalog Number, Part
Number and Serial Number. Separate the baseplate from the thermo-
stat to see additional manufacturing information.
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.