Lennox International Inc. 51M37 - Manual (Page 18)

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505049M 5/1/05
Maintenance Reminder
Settings of Off, 6 or 12 (months of chronological time) are
available. When programmed time has elapsed, a mainte-
nance indicator MAINT" is displayed.
Service Reminder
The SERVICE indicator is displayed only under the follow-
ing conditions:
S
if the thermostat Y1 terminal has been activated with
24VAC for at least 5 minutes, AND the L terminal is
shorted to the R terminal;
OR
S
if the thermostat Y1 terminal has been activated with
24VAC for at least 5 minutes, AND the L terminal is
shorted to the C terminal.
Power Loss/Recovery
Thermostat memory is retained for a minimum of 24 hours
during a power loss (includes retention of program infor-
mation, HOLD status, programmed temperature setpoint,
heat/cool and fan mode settings, filter reminder status,
maintenance reminder status, and equipment protection
timers). After 24 hours of power loss, programmed settings
will be lost and replaced with default settings.
IMPORTANT
Power must be applied for at least six consecutive
hours prior to a power loss in order for memory to
be retained for the specified time.
LCD Backlight
Activated for 30 seconds when any button is pressed.
NOTE − During an electrical storm or similar disturbance,
the backlight may activate for a few seconds. This is nor-
mal and will no longer occur after the electrical disturbance
has passed.
Thermostat Operating Conditions
35°F to 105°F, 5% to 90% RH
Thermostat Storage Conditions
−40°F to 185°F, 5% to 95% RH
Thermostat Output Table
Table 5 depicts the 51M35 thermostat output states for var-
ious input conditions. The following notes described terms
used in the table.
NOTE − X = output is activated with 24VAC.
NOTE − The temperature ranges expressed in the follow-
ing definitions of SMALL/LARGE" demands are for guid-
ance only; actual temperatures may vary.
With a small HEAT demand, temperature is:
below setpoint –0.5F but above setpoint –1.5F
AND 30-minute upstage timer HAS NOT expired.
With a large HEAT demand, temperature is:
less than setpoint –1.5F
OR 30-minute upstage timer HAS expired.
With a small COOL demand, temperature is:
above setpoint +0.5F but below setpoint +1.5F
AND 30-minute upstage timer HAS NOT expired.
With a large COOL demand, temperature is:
above setpoint +1.5F
OR 30-minute upstage timer HAS expired.
Table 5
Thermostat Outputs
Condition W1 W2 Y1 Y2 G
Gas Heat, Auto Fan
HEAT Demand, SMALL X
HEAT Demand, LARGE X X
COOL Demand, SMALL X X
COOL Demand, LARGE X X X
No Demand
Gas Heat, Continuous Fan
HEAT Demand, SMALL X X
HEAT Demand, LARGE X X X
COOL Demand, SMALL X X
COOL Demand, LARGE X X X
No Demand X
Electric Heat, Auto Fan
HEAT Demand, SMALL X X
HEAT Demand, LARGE X X X
COOL Demand, SMALL X X
COOL Demand, LARGE X X X
No Demand
Electric Heat, Continuous Fan
HEAT Demand, SMALL X X
HEAT Demand, LARGE X X X
COOL Demand, SMALL X X
COOL Demand, LARGE X X X
No Demand X