CONTROL PANEL OPERATING PROCEDURES
1. The DEMAND LED status indicator will light.
2. The unit checks to ensure that the Proof of
Closure (POC) switch in the downstream
Safety Shut-Off Valve (SSOV) is closed.
See Figure 3-3 for SSOV location.
TO AIR/FUEL
VALVE
SSOV
GA
INLET
MANUAL
SHUT-OFF
VALVE
Figure 3-3.
SSOV Location
3. With all required safety device switches
closed, a purge cycle will be initiated and the
following events will occur:
(a) The Blower relay energizes and turns
on blower.
(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) will read 100 to
indicate that it is full-open (100%).
(c) The VALVE POSITION bargraph will
show 100%.
4. Next, the blower proof switch on the Air/Fuel
Valve (Figure 3-5) closes. The display will
show Purging and indicate the elapsed time
of the purge cycle in seconds. The normal
(default) time for the purge cycle is 7
seconds.
5. Upon completion of the purge cycle, the
Control Box 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 (Figure 3-6) will read between 25
and 35 to indicate that the valve is in
the low-fire position.
(b) The igniter relay is activated and
provides ignition spark.
(c) The gas Safety Shut-Off Valve (SSOV)
is energized (opened) allowing gas to
flow into the Air/Fuel Valve.
Figure 3-4.
Air/Fuel Valve In Purge Position
Figure 3-5.
Blower Proof Switch
3-9
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