SYSTEM OPERATION
5
NORMAL SEQUENCE OF OPERATION
Power Up
1. 115 VAC power applied to furnace.
2. Integrated ignition control module performs internal
checks.
3. Integrated ignition control module LED will light.
4. Integrated ignition control monitors safety circuits
continuously.
5. Furnace awaits call from thermostat.
Normal Heating Sequence
1. R and W thermostat contacts close, initiating a call
for heat.
2. Integrated control module performs safety circuit
checks.
3. The induced draft blower is energized causing pres-
sure switch contacts to close. Induced draft blower
remains energized for pre-purge period.
4. Ignitor warm up begins after pre-purge is completed.
5. Gas valve opens at end of ignitor warm up period, de-
livering gas to burners to establish flame.
6.
The control checks for a signal from the flame sensor
within seven (4) seconds after the gas valve is ener-
gized. Gas will only continue to flow if a flame signal
is present.
7. Circulator blower is energized on heat speed following
a fixed thirty (30) second blower on delay.
8. Furnace runs, integrated control module monitors
safety circuits continously.
9. R and W thermostat contacts open, allowing the gas
valve to cycle off.
10.
Induced draft blower is de-energized following a fif
-
teen (15) - second post purge.
11. Circulator blower is de-energized following a selectable
heat off delay period (90, 120, 150 or 180 seconds).
12.
Furnace awaits next call from thermostat.
The adjustable delay-off timing allows the installer to cus
-
tomize the comfort level.
Cooling Mode
The normal operational sequence in cooling mode is as
follows:
1. R and Y thermostat contacts close, initiating a call for
cool.
2. Integrated control module performs safety circuit
checks.
3. Outdoor fan and compressor are energized.
4. Circulator blower is energized on cool speed following
a fixed five (7) second on delay.
5. Furnace circulator blower and outdoor cooling unit
run, integrated control module monitors safety circuits
continuously.
6. R and Y thermostat contacts open, completing the call
for cool.
7. Outdoor fan and compressor are de-energized.
8.
Circulator blower is de-energized following a fixed for
-
ty five (65) second cool off delay period.
9.
Furnace awaits next call from thermostat.
Fan Only Mode
The normal operational sequence in fan only mode is as
follows:
1. R and G thermostat contacts close, initiating a call for
fan.
2. Integrated control module performs safety circuit
checks.
3. Circulator blower is energized on
heat speed
.
4. Circulator blower runs, integrated control module
monitors safety circuits continuously.
5. R and G thermostat contacts open, completing the call
for fan.
6. Circulator blower is de-energized.
7.
Furnace awaits next call from thermostat.
ELECTRICAL CONNECTIONS
WARNING
To avoid the risk of electrical shock, wiring to the unit must
be properly polarized and grounded.
WARNING
HIGH VOLTAGE
Disconnect ALL power before servicing or in
-
stalling this unit. Multiple power sources may
be present. Failure to do so may cause proper
-
ty damage, personal injury or death.
CAUTION
Label all wires prior to disconnection when servicing
controls. Wiring errors can cause improper and dangerous
operation. Verify proper operation after servicing.
Wiring Harness
The wiring harness is an integral part of this furnace. Field
alteration to comply with electrical codes should not be re-
quired. Wires are color coded for identification purposes.
Refer to the wiring diagram for wire routings. If any of the
original wire as supplied with the furnace must be replaced,
it must be replaced with wiring material having a tempera-
ture rating of at least 105° C. Any replacement wiring must
be copper conductor.
115 Volt Line Connections
Before proceeding with electrical connections, ensure that
the supply voltage, frequency, and phase correspond to
that specified on the unit rating plate. Power supply to the
furnace must be N.E.C. Class 1, and must comply with all
