19
Midco International Inc.
8471 95
Part 2 Service - SCEBM-2 Module 120V
XI Burner Sequence
of Operation
for 120V Burners
Continued
B Interrupted
Sequence Version
120V Burners
END
45 or earlier
30
(30 second default)
31
0
Time Line in Seconds
Call for heat/Burner is Energized
Pre-purging sequence initialized:
• Relay “A” is energized
• SCEBM-2 Control will read “PRGE”
• Blower accelerates to high speed
• Low pressure air switch is closed
Pre-purging:
• Blower achieved high speed
• High pressure air switch is closed
• Flame safeguard is initialized and begins pre-purge
Pilot initialization:
• Flame safeguard initializes pilot
fl
ame for 10 seconds trial for ignition
• Pilot valve opened and spark initialized
• SCEBM-2 Control will read “PIL”
• Blower decelerates to lowest speed
Did the pilot
fl
ame light?
• Lockout
• Relay “A” is de-energized
• SCEBM-2 Control will read “OFF”
• Blower
stops
Lighting the main
fl
ame:
• Flame safeguard initializes main valve
• Main
fl
ame established at low
fi
re
• SCEBM-2 Control will read “IGN”
Heat Satis
fi
ed:
• Operating control opens
• All components shut o
ff
• SCEBM-2 control will read “OFF”
Yes
No
Modulation:
• Flame safeguard de-energizes pilot valve
• SCEBM-2 control will read “RUN”
• Burner begins modulating based on 2-10 VDC control signal
For 120V Models: Interrupted
__________________________________________
Chart 5 -
Interrupted 120V Sequence of Operation
