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18-CD32D1-3
Installer’s Guide
At the same time, the 2nd stage draft inducer is energized
and the 2nd stage pressure switch then closes. The 2nd
stage gas valve is then energized. (The inter-stage delay is
field selectable and can be adjusted through the User Inter-
face menu. It is factory set at 0 minutes but can be adjusted
to 5, 10, or 15 minutes.) This option can help optimize the
furnace to try to satisfy the heating requirement during low
heating load conditions.
Thermostat satisfied:
R and W thermostat contacts open signaling the heating
requirements have been satisfied. The gas valve is de-
energized and after a 5 second draft inducer post purge, the
draft inducer is de-energized.
If the inter-stage delay was met and the furnace was oper-
ating on 2nd stage heat, the indoor motor will operate at
2nd stage heating airflow for the duration of the 2nd stage
heating fan off delay.
If the furnace was operating on 1st stage heat, the indoor
motor will operate at 1st stage heating airflow for the dura-
tion of the 1st stage heating fan off delay.
Indoor Blower motor operation thermostat fan
switch “ON” (24V Mode)
R and G comfort control contacts close signaling a continu-
ous fan call. The continuous fan cfm is field selectable and
can be adjusted through the User Interface menu. The fac-
tory setting is 50% of the cooling cfm selected but can be set
at 25%, 50%, 75%, or 100%. If the system has a 2 stage out-
door unit, the setting is 50% of the 2nd stage cooling cfm.
Indoor Blower Timing:
The furnace control module (IFC) controls the variable
speed motor in the heating mode. The fan “ON” time is set
at 45 seconds and is not field selectable. The blower “OFF”
delay is factory set at 100 seconds and can be adjusted.
PERSONALITY MODULE
The Personality Module is a removable memory device, on
which is stored model specific data required for proper furnace
operation. The Personality Module is tethered to the unit and
must remain with the furnace at all times. The Personality
module must remain plugged into the furnace IFC.
UNIT TEST MODE
This furnace is equipped with a Unit Test mode that can be
accessed through the User Interface. See the User Interface
menu on how to enter this option. The test mode can be
performed in communicating or 24vac modes.
In communicating or 24vac modes, the unit test can only
be entered when there is not a heat, cool, continuous fan,
or circulation demands. If a heat demand occurs when the
unit test is running, the test mode will be aborted and the
normal heating sequence will be started. If a cooling, circu-
lator, or continuous fan demand occurs when the unit test
is running, the test mode will be completed before the other
demand is started.
All safety functions will be operable during the Unit Test
function. Any safety device that is triggered during the test
mode will terminate the test and the fault will be reported
in the Indoor Alerts and the Last Four Faults sections of
the user interface.
When the Unit Test option is activated, the unit will start
the indoor blower and energize the Y1 output. After ap-
proximately 10 seconds, the indoor blower and Y1 will turn
off. Next, the furnace will begin the ignition sequence.
After the flame has been sensed, the 45 second fan on delay
will be initiated. After the 45 second period, the indoor
blower is energized for 10 seconds in 1st stage heating
airflow. The furnace will then transition to 2nd stage gas
valve and blower operation for 10 seconds. The furnace will
then transition to off, running the normal post-purge and
the normal heat off delays.
If a button on the User Interface is pressed during the Unit
Test mode, the test will be terminated. The furnace will exit
the Unit Test mode and return to normal operation, auto-
matically, after 180 seconds of operation in Unit Test mode.
Communicating
Comfort Control
