Watts AERCO Benchmark BMK750 Operation And Service Manual page 36

Benchmark with Edge [I]: Operation-Maintenance Manual
SECTION 3 - START SEQUENCE
Start Sequence
BLOWER
PROOF
SWITCH
BLOCKED
INLET
SWITCH
Figure 3-4b: BMK1500 – 6000 Blower Proof Switch
6. Upon completion of the purge cycle, the Controller initiates an ignition cycle and the following events
occur:
a) he Air/Fuel Valve rotates to the low-fire (Ignition) position and closes the ignition switch.
T
The Dial on the Air/Fuel Valve (Figure 3-5) will read between 25 and 35 to indicate that
the valve is in the low fire position.
b) The Spark Cleaning cycle begins (default duration = 7 sec.) and the Ignition Sequence
screen's Spark Cleaning indicator (Figure 3-3) turns grey. This cycle turns on the ignition
transformer to produce a spark (with no gas flowing) to remove moisture and carbon
buildup from the spark element. For the duration of this cycle, the Controller displays the
Cleaning Igniter status message.
c) Following the Spark Cleaning cycle, power is applied to the gas Safety Shut-off Valve
(SSOV). When the SSOV indicates the Gas Valve is OPEN (POC) and the Ignition
Sequence screen's Ignition indicator (Figure 3-3) turns grey.
d) If no spark is present 3 seconds into the ignition trial, the Controller aborts the Ignition
Cycle and shuts down the boiler. Refer to Section 9: Troubleshooting in this guide for
guidance if this occurs.
OMM-0145_A99 • GF-218 •
AIR/FUEL VALVE
OUTLET TO BLOWER
Technical Support • (800) 526-0288 • Mon-Fri, 8 am - 5 pm EST
9/18/2019
AIR/FUEL VALVE
INLET FROM GAS
TRAIN
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