Page 37
TABLE 11
Thermostat Selection Switch Settings
Operation
Thermostat Switch 1 Switch 2 Switch 3
Variable Capacity Heat
(40% to 100%)
Two−Stage Off On Off
Three−Stage Heat
(40%, 70%, 100%)
Single−Stage On Off 2nd stage delay
OFF = 7 minutes
ON = 12 minutes
3rd stage delay
10 minutes fixed
Two−Stage Heat (W1 70%, W2 100%) Two−Stage Off Off Off
G71MPP units are equipped with a variable−capacity, vari-
able−speed integrated control. This control manages igni-
tion timing, combustion air inducer speed, heating mode
fan off delays and indoor blower speeds based on selec-
tions made using the control DIP switches and on−board
links. The control includes an internal watchguard feature
which automatically resets the ignition control when it has
been locked out.
Heating Operation DIP Switch Settings −− Figure 44
Switch 1 −− Thermostat Selection −− This unit may be used
with either a single−stage or two−stage thermostat. The
thermostat selection is made using a DIP switch which
must be properly positioned for the particular application.
The DIP switch is factory−positioned for use with a two−
stage thermostat. If a single−stage thermostat is to be used,
the DIP switch must be repositioned. See table 11.
Switch 2 −− Operating Mode with Two−Stage Thermo-
stat −− If a two−stage thermostat is used, the furnace can
operate in either variable−capacity or conventional two−
stage mode. When variable−capacity mode is selected, the
firing rate of the unit is varied to maximize comfort. Conven-
tional two−stage mode is the factory default setting. See
table 11.
Switch 3 −− Second−Stage Heat On Delay −− If a single−
stage thermostat is used, the integrated control can be
used to energize second−stage heat after either 7 minutes
or 12 minutes of first−stage heat operation. See table 11.
Switches 4 and 5 −− Blower−Off Delay −− The blower−on
delay of 45 seconds is not adjustable. The blower−off delay
(time that the blower operates after the heating demand
has been satisfied) can be adjusted by moving switches 4
and 5 on the integrated control. The unit is shipped from the
factory with a blower−off delay of 90 seconds. The blower
off delay affects comfort and is adjustable to satisfy individ-
ual applications. Adjust the blower off delay to achieve a
supply air temperature between 90° and 110°F at the exact
moment that the blower is de−energized. Longer off delay
settings provide lower supply air temperatures; shorter set-
tings provide higher supply air temperatures. Table 12 pro-
vides the blower off timings that will result from different
switch settings.
TABLE 12
Blower Off Delay Switch Settings
Blower Off Delay
(Seconds)
Switch 4 Switch 5
60 Off On
90 Off Off
120 On Off
180 On On
Indoor Blower Operation DIP Switch Settings
Switches 6 and 7 −− Continuous Indoor Fan Operation-
Blower Speed −− Switches 6 and 7 are used to select blow-
er motor speeds during continuous indoor blower opera-
tion. The unit is shipped from the factory with the DIP
switches positioned for medium low (2) speed during con-
tinuous indoor blower operation. The table below provides
the continuous blower speeds that will result from different
switch settings. Refer to tables 21 through 31 for corre-
sponding cfm values.
TABLE 13
Continuous Indoor Blower Operation −− Blower Speeds
Speed Switch 6 Switch 7
1 − Low Off On
2 − Medium Low
(Factory)
Off Off
3 − Medium High On Off
4 − High On On
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