62
The
OPR CTRL
LED indicates that there is power to the FSC. Next, the
AIRFLOW
LED will come on if
there is proper airflow through the unit. Third, the unit will pause to purge any gases or combustible vapors
before attempting flame ignition. Then, there is a Pilot Trial For Ignition (PTFI), and the
PTFI
LED comes
on. During PTFI, the FSC opens the pilot gas valve and allows gas to flow to the pilot assembly. At the
same moment, the spark igniter is started, causing the spark to ignite the pilot gas. When the flame rod
sensor detects the flame, it turns on the
FLAME
LED, turns off the PTFI LED, and powers the modulating
gas system. This is the system’s normal operating mode. The FSC continues to monitor the flame and
airflow. Once this occurs, the unit is in the main flame cycle and thus powers the main gas valve and the
modulating gas system. This is the normal operating mode. The FSC continues to monitor the flame and
airflow.
The last LED on the FSC is the
ALARM
LED. The alarm will turn on when the FSC determines an unsafe
condition has occurred and will not allow the unit to recycle for heat until it has properly been reset.
Anytime the FSC goes into “Alarm” mode, the issue must be diagnosed and corrected to avoid further
lockouts after resetting. If the unit fails to light the first time, the unit will try one more time before locking
out. This retry will not occur if the No FSC reset option is enabled. To begin troubleshooting, or to reset the
FSC, refer to
.
Figure 30 - Proper Spark Gap
1/8” to 3/16”
Proper Spark
Gap
Summary of Contents for MUA Controls
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