Thermostat output table – Lennox International Inc. 51M37 User Manual
Page 10
Page 10
505050M 5/1/05
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:
S X = output is activated with 24VAC.
S BBP: outdoor temperature is below balance point
S ABP: outdoor temperature is above balance point
S In all cases, the state of the B terminal is opposite that
of the O terminal
S Data are tabulated for AUTO fan setting. If the fan set-
ting is ON, the G output is activated in all cases
S Upstage timers:
30 minutes (when upstaging from small to large
demand)
15 minutes (HEAT MODE ONLY − when upstaging
from large to very large demand)
S The temperature ranges expressed in the following
definitions of SMALL/LARGE/VERY 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 2
nd
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