Specifications are subject to change without notice.
35
441 01 7201 00
Sequence of Operation - Heating
1.
Call for Heat
A call for heat is intiated when a connection is observed
between thermostat terminals “R” & “W”.
a.
Pressure Sensor Verification:
The control operates the
inducer in a manner to verify the pressure sensor null
value and span operation are within specification. If the
system is operating correctly, this test takes only a few
seconds. If the system is not functioning properly, the
control times out after a maximum 90 seconds and
displays the proper fault code.
b.
Pre-purge:
The heating cycle begins with operation of
the inducer at “Pre-purge” setting for the 30 seconds.
c.
Igniter Warm-Up:
After the pre-purge timer expires,
the control will set the inducer to the “Ignitor Warm-Up”
setting and energize the igniter for the Igniter Warm-up
period of 17 seconds.
NOTE
:
Inducer motor shuts off during igniter warm up period
and then come back on for the ignition trial.
d.
Trial for Ignition:
Once the igniter warm-up period has
expired, the control sets the inducer to the “Trial for
Ignition” setting and stabilizes the inducer speed to meet
the target pressure. The gas valve is then energized
allowing the flow of gas to the burner. The gas valve
remains open for the Trial for Ignition interva
l.
e.
Flame Sense:
While the gas valve is open, the control
monitors the flame sense circuit to detect the presence of
flame. If flame is not established during the Trial for
Ignition period of 4 seconds, the control de-energizes the
gas valve and operates the inducer for the Inter-purge
period.
f.
Flame Stabilization:
Once flame is established, the
control will set the inducer to the “Flame Stabilization”
setting and maintain the inducer operation at this setting
for the duration of the Flame Stabilization timing of 10
seconds.
g.
Blower On-Delay:
Once a successful ignition occurs,
the control will wait for the Heat Blower On-Delay of 25
seconds (time begins when the gas valve is energized) and
then energize the blower heating speed.
h.
Heating Cycle Run:
After the Flame Stabilization
period is completed, the control will continue to maintain
the heating cycle with the inducer running at the “Run”
setting until one of the following occurs:
(1.)
The call for heat is satisfied (the connection between
“R” & “W” is removed).
(2.)
Flame sense is lost (flame out), in which case the
control will initiate an inter-purge (45s) and recycle.
(3.)
A lockout condition exists, in which case the control
terminates the heating call and waits for the error
condition to resolve according to the programmed
parameters.
i.
Post-purge:
Once the burner cycle has terminated and
loss of flame is verified, the control energizes the inducer
at the “Post-purge” setting for 30s.
j.
Inter-purge:
In the event of a failed trial for ignition, the
control energizes the inducer at the “Post-purge” setting
for the Inter-purge Timing 45s.
k.
Blower Off-Delay:
Once the gas valve has been
de-energized, the control continues to operate the blower
on the HEAT speed for the duration of the Heat Blower
Off-Delay timing. The Heat Blower Off-Delay is
field-selectable (90, *120, 150, 180).
NOTE
:
*120 is default setting.
OFF:
The controls returns to the stand- by mode until either a
thermostat call is received or an error condition occurs.
Sequence of Operation - Cooling
1.
Call for Cool
A call for heat is intiated when a connection is observed
between thermostat terminals “R” & “Y”.
a.
Blower On-Delay:
When the call for cool is initiated,
the control will wait for the Cooling Blower On-Delay
timing of 2 seconds, for both jumper settings.
b.
Blower Off-Delay:
Once the connection between “R”
and “Y” is removed, the control continues to operate the
blower on the COOL speed for the duration of the Cool
Blower Off-Delay timing (fixed 90 seconds).
OFF:
The controls returns to the stand- by mode until either a
thermostat call is received or an error condition occurs.
Sequence of Operation - Fan Only
1.
Operation:
Fan Only Mode is initiated when a
connection is observed between thermostat terminals “R”
& “G”. The “G” terminal is ignored when there is either a
call for heat or call for cool. When in the Fan Only Mode,
the blower will be energized to run on Fan speed.
Fault Code Recall
1.
Function:
When the SW1 button is pressed momentarily,
the control displays the last five (5) fault codes recorded in
non-volatile memory upon demand.
2.
Operation:
The control must be powered and the
thermostat satisfied (no call for heat or cool). Depress and
release the SW1 button once (less than 5 seconds); the
LED will flash the Fault Code History (up to 5 fault codes
from newest to oldest)
NOTE
:
Fault Code Display Means:
Multi-Color LED (Green,
Amber, Red).
Clear Fault Memory
1.
Function:
When the SW1 button is pressed and held for
an extended period (more than 5 seconds, less than 10
seconds), the control erases the stored fault code history.
2.
Operation:
The control must be powered and the
thermostat satisfied (no call for heat or cool). Depress and
hold the SW1 button for at least 5 seconds (but not more
than 10 seconds), until the LED flashes a rapid Green,
then release. The fault code history will be erased.
Component Test
1.
Function:
When the SW1 button is pressed and held for
an extended period of time (more than 10 seconds, less
than 15 seconds), the control will initiate a component
self test.
2.
Operation:
The control must be powered and the
thermostat satisfied (no call for heat or cool). Depress and
hold the SW1 button for at least 10 seconds (but not more
than 15 seconds), until the LED flashes Amber, then
release. The control will execute the following functions:
a.
Inducer starts and runs throughout the entire test
b.
Hot surface igniter on for 15 seconds, then off
c.
Blower motor will be turned on at constant fan speed, heat
speed, and cool speed for 15 seconds each.
d.
Control returns to standby mode.
NOTE
:
If SW1 button is held for longer than 15 seconds, the
control will remain in standby mode
Wiring Diagrams
Refer to Fig. 38 for wiring diagram.
Troubleshooting
Refer to the service label. (Fig. 35), wiring diagram (Fig. 38), and
the Service Guide (Page 37) can be a useful tool in isolating
furnace operation problems. The Guide will help to identify the
problem or failed component. After replacing any component,
verify correct operation sequence.
