Troubleshooting
7-4
750-91 (revised 2009)
Model CB-LE Packaged Boiler Manual
SHUTDOWN OCCURS
DURING FIRING
1. Loss or stoppage of fuel supply.
2. Defective fuel valve, loose electrical connection.
3. Flame detector weak or defective.
4. Lens dirty or sight tube obstructed.
5. If the programmer lockout switch has not tripped, check the limit circuit for
an opened safety control.
6. If the programmer lockout switch has tripped:
A. Check fuel lines and valves.
B. Check flame detector.
C. Check for open circuit in running interlock circuit.
D. The flame failure light is energized by ignition failure, main flame failure,
inadequate flame signal, or open control in the running interlock circuit.
7. Improper air/fuel ratio (lean fire):
A. Slipping linkage.
B. Damper stuck open.
C. Fluctuating fuel supply:
1) Temporary obstruction in fuel line.
2) Temporary drop in gas pressure.
3) Orifice gate valve open.
8. Interlock device inoperative or defective.
MODULATING MOTOR
DOES NOT OPERATE
1. Manual-automatic switch in wrong position.
2. Linkage loose or jammed.
3. Motor does not drive to open or close during pre-purge or close on burner
shutdown:
A. Motor defective.
B. Loose electrical connection.
C. Damper motor transformer defective.
4. Motor does not operate on demand:
A. Manual-automatic switch in wrong position.
B. Modulating control improperly set or inoperative.
C. Motor defective.
D. Loose electrical connection.
E.Damper motor transformer defective.
Problem Possible Cause(s)
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