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6) Once the ignition module detects the presence of a pilot flame, voltage is applied across the main valve, opening
the valve and establishing main flame.
7) The way in which the ignition module handles failure to establish pilot or the loss of an already established pilot
depends upon the exact ignition module supplied with the boiler. For more information on module operation,
consult the ignition module instructions supplied with the boiler or the local Crown representative.
Sequence of Operation – CSD-1 Boiler Wiring
1) All low water cut-offs, limit controls, and the operating contacts are wired in series so that the boiler will not
operate if any of these controls are open. Under normal circumstances, only the operating control contacts will be
open.
2) Upon a call for heat, the operating control will make and 120 volts will be applied to all base module transformers,
which are wired in parallel.
3) 24 volts will then appear across the “24V” and “24V (GND)” terminals on the ignition modules and on the
“24VAC” and “COM” terminals on the 1145-2 Daughter Board.
4) The ignition module will start an ignition spark at the pilot and apply 24 volts across the pilot valve.
5) Once a pilot is established, the pilot flame will act as a diode, converting AC current at the pilot electrode to a half
wave DC current at the pilot’s ground strap. This DC current flows through the boiler to the “GND” terminal on
the ignition module.
6) Once the ignition module detects the presence of a pilot flame, voltage is applied across the main valve, opening
the valve and establishing main flame.
7) If the pilot flame is not established during the trial for ignition period, or if the pilot signal is lost after the main
flame is established, the module will de-energize the open pilot valve and main valve (if open) and wait 5 minutes.
It will then repeat steps 4-6. If the pilot is still not established, the Alarm contacts on the ignition module will
make. This will cause the 1145-2 Daughter Board to break power to the ignition module and illuminate the red
LED on the Daughter Board. The ignition module will remain de-energized until the reset button on the daughter
board is pressed.
Figure 34: Typical Wire Routing