Flow Diagrams - Lennox SignatureS
tat 81M26 Programming And Application Manual

Fan Auto
In COOLING, the indoor blower cycles with calls for Cooling.
In HEAT, and with the thermostat set for standard, the indoor blower (G)
cycles with a call for first stage of heating. Note the indoor blower and com-
pressor stay on when the second stage of heating activates.
GO TO: MENU > INSTALLER SETTINGS > SYSTEM SETUP > STANDARD−COMP=ON
When in add−on heat, the indoor blower (G) again cycles with the call for
first stage heat. Note that the compressor turns off (comp=off) when the
second stage of heat activates, but the indoor blower remains on.
GO TO: MENU > INSTALLER SETTINGS > SYSTEM SETUP > ADD ON−COMP=OFF
Fan ON
The indoor blower is ON continuously regardless of whether
the heating or cooling equipment is running.
Thermostat Off" Mode
In this mode, the heating and cooling and
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.
System Setup
Default setting is STD (STANDARD−COMP=ON). The
auxiliary heat may be configured for standard or ADD on. Standard means
the auxiliary stage supplements the compressor stage (the compressor
and auxiliary are on at the same time). Add−on (ADD ON−COMP=OFF)
means that the compressor turns off before the auxiliary turns on. When the
auxiliary turns off, the compressor may turn on again.
Low Balance Point
Default setting is 25°F. This option will only be
available if an outdoor sensor is installed. If the outside temperature is be-
low the programmed low balance point, then the compressor stage opera-
tion is disallowed. This protects the compressor from operation and dam-
age in cold outdoor temperatures. Also, if the heat pump is not effective at a
low outdoor temperature, then it is more comfortable and efficient to go di-
rectly to the second stage. The options are from −20°F to the high balance
point temperature in 1.0°F steps.
High Balance Point
Default setting is 50°F. This option is only avail-
able if an outdoor sensor is installed. If the outside temperature is above the
high balance point, then the auxiliary heat stage is disallowed. This pre-
vents the expensive auxiliary heat stage from operating, and makes the low
cost heat pump satisfy the call. Both the compressor and auxiliary heat may
not be disabled at the same time by the low and high balance points.
SignatureStatt Humiditrol
81M SignatureStatt Equipment
Operation with Humiditrol
IMPORTANT!
®
HUMIDITROL IS
NOT ALLOWED TO
RUN EQUIPMENT
RUN IF:
S OUTDOOR
TEMPERATURE
IS GREATER
THAN 95ºF
OR,
S INDOOR
RUN EQUIPMENT
TEMPERATURE
IS LESS THAN
65ºF.
COOLSET – DBND
LEGEND:
COOLSET = COOLING SETPOINT
DBND = DEADBAND
HEATSET = HEATING SETPOINT
INTEMP = INDOOR TEMPERATURE
Page 25
®
Logic Diagram
start
®
Enabled
IS THERE A
IN NORMAL
COOLING
COOLING MODE
YES DEMAND?
NO
IS THERE A
IN NORMAL HEATING
HEATING MODE DEMAND?
YES
NO
DEACTIVATE
IS THERE A
ALL
DEHUMIDIFICATION
EQUIPMENT
DEMAND?
NO
YES
NO
IS INTEMP > IS
COOLSET – HEATSET
NO
+2ºF > DBND
? ?
YES
YES
IS INTEMP >
NO
2ºF ABOVE
HEATSET
?
Figure 6
SignatureStat t Thermostat
run
®
Humiditrol
YES