Lennox International Inc 51M37 operation manual Smart Setback Recovery via DIP switch #6

Smart Setback Recovery (via DIP switch #6)

Smart Setback Recovery (SSR) affects the way the ther- mostat responds to program events. If SSR is disabled, the thermostat will react to a program event at the time the event occurs. However, if SSR is enabled, the thermostat will react to a program event before the event occurs such that the desired temperature is reached at the time of the event, not after.

Autochangeover Deadband Selection (via DIP switch #7)

Autochangeover deadband can be set to 4 or 6 degrees. When autochangeover is enabled (via the AUTO button), the thermostat will automatically change over from heating to cooling and vice versa, to keep the room temperature in between the heating and cooling setpoints. The deadband is the minimum difference between the heating and cooling setpoints.

Fan Control

AUTO or ON modes, gas or electric heat compatible via DIP switches (also see Thermostat Output section).

I/O Relays

All thermostat relays are latching type to minimize power consumption.

Table 5

51M38 Terminal Designations

Terminal Description

R24VAC

Y1	First stage cooling
W1	First stage heating

GFan control

LService Indicator

C24VAC common

TOutdoor temperature sensor connection 1

TOutdoor temperature sensor connection 2

Equipment Protection Timers

Minimum Compressor OFF time: 5 minutes

Minimum Compressor ON time: 4 minutes

Minimum Furnace ON time: 3 minutes

Minimum furnace cycle time (elapsed time between any furnace activation and the next furnace activation): 6 min- utes.

Minimum elapsed time between any compressor activa- tion and the next compressor activation: 6 minutes.

NOTE − All protection timers (except the compressor OFF timer) can be over−ridden if a heating or cooling demand is initiated or terminated using the UP, DOWN, HEAT, or COOL buttons.

Equipment Protection Override

Both the minimum compressor OFF timer and the mini- mum equipment cycle timer can be over−ridden by press- ing and holding either the HEAT or COOL button down for 4 seconds.

Over−Temperature Protection

Thermal-mechanical switch opens W1 at 93°F+/−6°F.

Filter Reminder

Settings of Off, 1, 3, 6 or 12 (months of fan run time) are available. When programmed time has elapsed, a FILTER indicator is displayed.

Maintenance Reminder

Settings of Off, 6 or 12 (months of chronological time) are available. When programmed time has elapsed, a MAIN- TENANCE indicator is displayed.

Service Reminder

The SERVICE indicator is displayed only under the follow- ing conditions:

Sif 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

Sif 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 clock setting, program information, HOLD status, programmed temper- ature setpoint, heat/cool and fan mode settings, filter re- minder status, maintenance reminder status, and equip- ment 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

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505067M 7/13/05