TABLE 11
Thermostat Selection Switch Settings
Operation Thermostat Switch 1 Switch 2 Switch 3
Variable Capacity Heat Two-Stage Off On Off
(40% to 100%)
Three-Stage Heat Single-Stage On Off 2nd stage delay
(40%, 70%, 100%) 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, van-
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 42
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 Switch 4 Switch 5
(Seconds)
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
Off Off
(Factory)
3 - Medium High On Off
4 - High On On
Page 34
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