Service manual

SC Series Boilers – Installation and Service Manual
35
Problem Possible Cause Solution
• No spark or no hot surface glow.
• High voltage wiring is loose, broken or
grounded. Repair wiring.
• Ignition electrodes or H.S. are damaged. • Replace electrodes or igniter.
• Ignition electrodes improperly adjusted. • Correct adjustment of electrode.
• Faulty electronic ignition controller. • Replace controller.
• No gas.
• Confirm supply of gas to pilot and repair if
necessary.
• Gas supply pipes not purged of air. • Purge gas line.
• Air pressure switch is damaged. • Replace air pressure switch.
Main burner will not light
• Dirt or foreign material on the electrodes. • Clean.
• Incorrect manifold pressure. • Set manifold pressure to correct pressure.
• Poor connections in wiring to flame sensor. • Repair wiring.
• Air differential pressure is set to high.
• Adjust the air shutter and set air differential
pressure to correct pressure.
Spark or hot surface
proves but flame failure
after trial for ignition.
• Ignition electrodes improperly adjusted. • Correct adjustment of electrodes.
• Ignition electrodes are wet, dirty or
improperly adjusted (for electronic ignition
only).
• Check, clean, change and/or adjust the
electrodes.
• Reversed polarity of power supply. • Check the power supply polarity
• Air differential pressure is too high.
• Adjust the air shutter and set air differential
pressure to correct pressure.
Burner starts but flame
will not stay established.
• Poor connections in wiring to flame sensor. • Repair wiring.
• Incorrect orifice sizing. • Check orifice and replace if necessary.
• Inadequate combustion air. • Check and adjust air differential pressure.
• Dusty environment. • Clean.
• Low return water temperature. • Adjust system.
Boiler carbonizes (forms
soot) quickly.
• Manifold pressure too high. • Adjust manifold pressure.
• Insufficient circulation.
• Check pump, clean and replace if necessary.
• Air trapped in piping. • Purge system.
Boiler overheats and
system remains cold.
• Improper system wiring. • Test and correct.
• Faulty thermostat or controller. • Check, adjust, and replace if necessary.
• Faulty aquastat and/or safety high limit
aquastat.
• Check, adjust, and replace if necessary.
Boiler and heating system
overheat.
• Faulty wiring. • Check wiring for short circuits and repair.
8.2 CONTROL TROUBLESHOOTING
8.2.1 Hot Surface and Direct Spark Ignition System with Fenwal Module
a) Fault Conditions of Hot Surface and Direct Spark Ignition System
Carefully note the red diagnostic indicator light located on the Fenwal Module. When a system failure
occurs, the indicator light will show a series of quick flashes followed by a short pause between the series
of quick flashes. Count the number of flashes that occur between the short no-flashing intervals. The
failure code for the number of flashes and service checks are shown in following tables.