Lennox International Inc 51M37 Thermostat Output Table, Table THERMOSTAT OUTPUTS, Cooling Demands

Thermostat Output Table

Table 5 depicts the 51M37 thermostat output states for var- ious input conditions. The following notes described terms used in the table.

NOTES:

SX = output is activated with 24VAC.

SBBP: outdoor temperature is below balance point

SABP: outdoor temperature is above balance point

SIn all cases, the state of the B terminal is opposite that of the O terminal

SData are tabulated for AUTO fan setting. If the fan set- ting is ON, the G output is activated in all cases

SUpstage timers:

30 minutes (when upstaging from small to large demand)

15 minutes (HEAT MODE ONLY − when upstaging from large to very large demand)

SThe temperature ranges expressed in the following definitions of Y LARGE" de-

mands are for guidance 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 very large heat demand, temperature is:

below setpoint –2.5F

OR 15−minute 2nd upstage timer HAS expired.

Emergency heat demand (only if emergency heat is enabled): temperature is below setpoint –0.5F.

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

Demand Condition W1 E Y1 Y2 G O

Cooling Demands

SMALL				X		X	X
LARGE				X	X	X	X
No Demand							X
	Heating Demands
w/Electric Backup (no outdoor sensor)
SMALL				X		X
LARGE				X	X	X
Very LARGE		X		X	X	X
Emergency			X			X
No Demand

w/Gas Backup (dual fuel; no outdoor sensor)

SMALL			X		X
LARGE			X	X	X
Very LARGE	X
Emergency		X
No Demand
w/Electric Backup (outdoor sensor attached)
SMALL (Above Balance Point)			X		X
LARGE (ABP)			X	X	X
Very LARGE (ABP)			X	X	X
SMALL (Below Balance Point)			X		X
LARGE (BBP)			X	X	X
Very LARGE (BBP)	X		X	X	X
Emergency		X			X
No Demand

w/Gas Backup (dual fuel; outdoor sensor attached)

SMALL (ABP)			X		X
LARGE (ABP)			X	X	X
Very LARGE (ABP)	X
SMALL (BBP)	X
LARGE (BBP)	X
Very LARGE (BBP)	X
Emergency		X
No Demand

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