SEQUENCE OF OPERATION
Thermostat call for heat (2-stage thermostat)
Call for 1st stage only:
W1 thermostat contacts close signaling the control module to
run its self-check routine. After the control module has
verified that the 1st stage pressure switch contacts are open
and the limit switch(es) contacts are closed, the draft blower
will be energized.
As the induced draft blower comes up to speed, the pressure
switch contacts will close and the ignitor warm up period will
begin. The ignitor will heat for approx. 20 seconds, then the
gas valve is energized in 1st stage to permit gas flow to the
The flame sensor confirms that ignition has been achieved
within the 4 second ignition trial period.
As the flame sensor confirms that ignition has been achieved,
the delay to fan ON period begins timing and after approx. 45
seconds the indoor blower motor will be energized at low
speed and will continue to run during the heating cycle.
Call for 2nd stage after 1st stage:
W2 thermostat contacts close signaling a call for 2nd stage
heat. After a 30 second delay, the induced draft blower will
be energized on high speed and the 2nd stage pressure
switch contacts will close. The gas valve is energized in
2nd stage and the indoor blower motor in high speed.
2nd stage satisfied, 1st stage still called:
W2 thermostat contacts open signaling that 2nd stage
heating requirements are satisfied.
The induced draft blower is reduced to low speed allowing
the 2nd stage pressure switch contacts to open and the gas
valve is reduced to 1st stage. The indoor blower motor is
reduced to low speed.
1st stage satisfied:
W1 thermostat contacts open signaling that 1st stage
heating requirements are satisfied. The gas valve will close
and the induced draft blower will be de-energized. The
indoor blower motor will continue to run for the fan off period
(Field selectable at 60, 100, 140 or 180 seconds), then will be
de-energized by the control module.
Thermostat call for heat (1-stage Thermostat)
W1/W2 (jumpered) thermostat contacts close signaling a call
for heat. 1st stage sequence of operation remains the same as
above. 2nd stage heat will energize after the stage delay
timer (field selectable at .5, 5, 10 or 15 minutes) has expired.
W1/W2 (jumpered) contacts open signaling the control
module to close the gas valve. The induced draft blower is
switched to low speed and de-energized after the post purge
timer has expired. The indoor blower motor will continue to
operate after the flames are extinguished and then is
switched to low heat speed for the FAN-OFF period.
Should overheating occur, or the gas supply fail to shut off,
shut off the gas valve to the unit before shutting off the
electrical supply. Failure to follow this warning could result
in property damage, personal injury, or death.
Indoor blower operation with thermostat fan switch "ON":
Fan is R-G.
R-W energized, fan continues to run without interruption.
Heat Low speed if it is a two stage furnace.
Heat speed if it is a single stage furnace.
INDOOR BLOWER TIMING
Heating: The integrated furnace control module controls
the indoor blower. The blower start is fixed at 45 seconds
after ignition. The FAN-OFF period is field selectable by
dip switches SW-2, #1 and #2 at 60, 100, 140, or 180
seconds. The factory setting is 100 seconds.
W1-W2 stage delay (jumpered together) is field selectable by
dip switch SW-1, #1 and #2 at .5, 5, 10 or 15 minutes. The
factory setting is 10 minutes. (See wiring diagram).
Cooling: The fan delay-off period is set by dip switches on
the Integrated Furnace Control. The options for cooling
delay off is field selectable by dip switches #5 and #6.
The following table and graph explain the delay-off settings:
COOLING OFF - DELAY OPTIONS
5 - OFF
6 - OFF
5 - ON
6 - OFF
5 - OFF
6 - ON
5 - ON
6 - ON
* - This setting is equivalent to BAY24X045 relay benefit
** - This selection provides ENHANCED MODE, which is a
ramping up and ramping down of the blower speed to provide
improved comfort, quietness, and potential energy savings.
See Wiring Diagram notes on the unit or in the Service Facts
for complete wiring setup for ENHANCED MODE. The graph
which follows, shows the ramping process.
Fast Coil Cooling
BODILY INJURY CAN RESULT FROM HIGH VOLTAGE
ELECTRICAL COMPONENTS, FAST MOVING FANS, AND
COMBUSTIBLE GAS. FOR PROTECTION FROM THESE
INHERENT HAZARDS DURING INSTALLATION AND
SERVICING, THE ELECTRICAL SUPPLY MUST BE
DISCONNECTED AND THE MAIN GAS VALVE MUST BE
TURNED OFF. IF OPERATING CHECKS MUST BE PER-
FORMED WITH THE UNIT OPERATING, IT IS THE
TECHNICIAN'S RESPONSIBILITY TO RECOGNIZE THESE
HAZARDS AND PROCEED SAFELY.
The integrated furnace control is polarity sensitive. The hot
leg of the 115 VAC power must be connected to the BLACK
50 - 100%
100% if necessary