54
10. When the initial timer in TR1 times out, it defaults the gas
valve to low fire and the combustion blower to low speed and
returns control of the operating mode to the temperature con
-
troller. The SR LED turns off and the MR LED is lit.
11. If the controller is calling for second stage heat TR1 terminal
6 is powered. After a short time delay (approximately 15 sec
-
onds), the system switches the combustion blower to high
speed (FR LED lit) and the second stage gas valve at 3.5 in.
wg manifold pressure (CR LED lit), provided the High Air
Pressure Switch (APS2) is proved.
12. During heating operation, the thermostat, pressure switch and
main burner flame are constantly monitored by the IC to
assure proper system operation.
13. Operation continues on High fire until the second stage ther
-
mostat is satisfied, opening the second stage contact and de-
energizes terminal 6 on the TR1, turning off the second stage
gas valve and returning the combustion blower to low speed.
14. When the thermostat (controller) is satisfied and the demand
for heat ends, the first stage valve is de-energized immedi
-
ately, the control senses loss of flame and a 30-second post-
purge occurs (at high speed) before de-energizing the com
-
bustion blower.
IGNITION AND OPERATIONAL FAILURES DURING A
CALL FOR HEAT RESULT IN “LOCKOUT” OF THE IGNI
-
TION CONTROL
1. If flame is lost during an operational cycle, the control will
respond within 0.8 seconds. The spark will be energized for a
trial for ignition period to attempt to relight burners and prove
flame sensor. If flame is re-established, normal operation
resumes.
2. If the burners fail to light or carryover during a trial for igni
-
tion, the control will attempt two additional ignition trials. If
no flame is present at the flame sensor within 10 seconds, the
spark and gas valve will be de-energized. A 15-second inter-
purge period begins and the combustion blower continues to
run. After the inter-purge period another ignition trial will
take place.
3. If burner fails to light or prove the flame sensor following the
two additional trials the control will go into lockout. The
valve relay in the IC will be de-energized, shutting of the gas
valve immediately and the combustion blower following a
30-second post-purge period.
RECOVERY FROM LOCKOUT
1. If the thermostat (controller) is still calling for heat one hour
after a lockout occurs, the control will automatically reset and
initiate a call for heat sequence.
2. The ignition control may also be manually reset, by turning
the thermostat (controller) down and back up to previous
temperature setting or removing power (24V) to IC terminal
24VAC.
IC FAULT CONDITIONS AND LED KEY
Table 24 lists LED flashing codes and their meanings.
Table 24 — LED Codes
NOTE: LED flashes on for 1/4 second, and off for 1/4 second during
fault condition. Pause between fault codes is 3 seconds.
1. If during the initial call for heat the air switch contacts are
closed for 30 seconds without an output to the combustion
blower, an airflow fault occurs (one LED flash) and control
will remain in this mode.
2. If the airflow switch remains open (or a rollout switch is
open) for more than 30 seconds after the combustion blower
output (IND) is energized, an airflow fault occurs (one LED
flash), and control will stay in this mode with combustion
blower on, waiting for airflow switch (or rollout) to close.
3. If the airflow signal is lost during operation, the control
immediately de-energizes the gas valve and maintains blower
operation. If the call for heat remains and proper airflow is
not detected, and airflow fault occurs (one LED flash). If
proper airflow is detected at any time, the normal sequence
will begin with pre-purge.
4. If the main valve fails to close properly at the end of a heating
cycle and a flame is maintained, the combustion blower will
continue in operation. If the valve does close completely later
removing the flame signal, the blower will run for the post
purge period and shut off.
LED
MEANING
LED Steady On
Internal Control Fault
1 Flash
Combustion Air Flow Fault
2 Flash
Flame with No Call for Heat
3 Flash
Ignition Lockout