Lennox International Inc 51M37 Removing and Installing Thermostat, Default Thermostat Settings

Removing and Installing Thermostat

The thermostat hinges on tabs on the top of the subbase; no tool is needed to remove the thermostat from the sub- base. Pivot the bottom of the thermostat outward (releas- ing the snaps), then lift up to remove.

To install it, first position the top tilted toward the wall brack- et and align it until you feel the tabs and slots engage; then, while the top is in place, pivot the bottom toward the wall until the thermostat snaps into place.

Default Thermostat Settings

Default thermostat settings are in table 2 and the default program is shown in table 3.

Table 2

Default Thermostat Settings

Mode	Heat (Perm. Hold)
Heat Setpoint (Perm Hold)	70°F (or 21°C)
Cool Setpoint (Perm Hold)	78°F (or 26°C)
Fan	Auto
Filter Reminder	OFF
Maintenance Reminder	OFF
Equipment Protection Timers	Reset Back to Zero
Autochangeover	OFF

Table 3

Default Program Settings (Time & Temp.)

Programs	Time	Temp.− Heat	Temp.− Cool
All days − A	6:00am	70_F / 21°C	78_F / 26°C
All days − B	8:00am	62_F / 17°C	85_F / 29°C
All days − C	6:00pm	70_F / 21°C	78_F / 26°C
All days − D	10:00pm	62_F / 17°C	82_F / 28°C

Thermostat Output Table

Table 4 depicts the 51M39 thermostat output states for var- ious input conditions. The following notes described terms used in the table.

Table 4

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

NOTE − X = output is activated with 24VAC.

NOTE − The temperature ranges expressed in the follow- ing definitions of

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.

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51M39 SERIES 5/2