Lennox SignatureS
tat 81M26 Programming And Application Manual page 23

81M27 2 Stage Heat & Cool, Non−Heat Pump
Table 4. 81M27 LED Indicators
COOL Cooling mode (Y is active)
CHECK 24V signal is present on the L" terminal
HEAT Heating mode (W1 is active)
Table 5. 81M27 Terminal Designations
R 24 Vac power input from HVAC system
C 24 Vac common
Y1 Energized on call for 1st stage COOL
Y2 Energized on call for 2nd stage COOL
E/W1 Energized on for 1st stage HEAT
W2 Energized on for 2nd stage HEAT
G Energized on call for FAN
H Energized on a call for humidification
D De−energized on a call for dehumidification (reverse logic)
O COOL active (always energized when the stat is in COOL mode,
default value is OFF)
B HEAT active (always energized when the stat is in HEAT mode,
default value is ON)
L Illuminates CHECK LED when energized with 24VAC
NOTE − High−temperature PEPI disables W1 ands W2 when ambient tem-
perature exceeds 95F.
Fan Auto
In COOLING, the indoor blower cycles with calls for cooling.
In HEAT, and with the thermostat set for gas/oil, the indoor blower (G) does
not cycle with a call for heat. The independent fan control in the flue will
cycle the indoor blower as necessary.
GO TO: MENU > INSTALLER SETTINGS > SYSTEM SETUP > GAS/OIL
When in electric heat, the indoor blower (G) cycles with the call for heat.
GO TO: MENU > INSTALLER SETTINGS > SYSTEM SETUP > ELECTRIC
Fan ON
The indoor blower is ON continuously regardless of whether
the heating or cooling equipment is running.
Thermostat Off" Mode
H/D terminals are inactive. The O or B terminal is active. This is determined
by the last state of O/B. For example, if the mode goes from heat (B active)
to off, then B will be active in the off mode. Default on power−up is B active.
The G terminal may be active if FAN ON is selected from the menu.
81M28 2 Stage Heat & Cool Heat Pump
Table 6. 81M28 LED Indicators
AUX W2 is active.
CHECK 24V signal is present on the L" terminal
EMER Emergency heat is enabled in menu.
Table 7. 81M28 Terminal Designations
R 24 Vac power input from HVAC system
C 24 Vac common
Y1 Energized on for 1st stage HEAT or COOL (heat pump com-
pressor control)
Y2 Energized on call for 2nd stage COOL
E/W1* Energized on call for emergency heat
W2* Energized on for 2nd stage HEAT
G Energized on call for FAN
H Energized on a call for humidification
D De−energized on a call for dehumidification (reverse logic)
O COOL active (always energized when the stat is in COOL
mode, default value is OFF)
B HEAT active (always energized when the stat is in HEAT
mode, default value is ON)
L Illuminates CHECK LED when energized with 24VAC
* Factory-installed jumper between E/W1 and W2.
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In this mode, the heating and cooling and
SignatureStat t Thermostat