b. The Air/Fuel Valve rotates to the full-open purge position and closes purge position
switch. The dial on the Air/Fuel Valve (Figure 3.4-2) will read 100 to indicate that it
is full-open (100%).
c. The VALVE POSITION bargraph will show 100%.
Figure 3.4-2: Air/Fuel Valve in Purge Position
4. Next, the Blower Proof switch on the Air/Fuel Valve (Figure 3.4-3) closes. The display will
show PURGING and indicate the elapsed time of the purge cycle in seconds.
Figure 3.4-3: Blower Proof Switch
5. Upon completion of the purge cycle, the Edge Controller initiates an ignition cycle and the
following events occur:
a. The Air/Fuel Valve rotates to the low-fire ignition position and closes the Ignition
switch. The dial on the Air/Fuel Valve will read between 25 and 35 (Figure 3.4-4)
to indicate that the valve is in the low-fire position.
b. The igniter-injector relay is activated and provides ignition spark. Current to the
igniter or igniter-injector is monitored by the spark monitor (P/N 61034).
c. The gas Safety Shut-Off Valve (SSOV) is energized (opened) allowing gas to flow
into the Air/Fuel Valve.
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