Additional Faults Without Specific Fault Messages - Watts AERCO Benchmark BMK750 Operation And Service Manual

Benchmark with Edge [I]: Operation-Maintenance Manual
SECTION 9 – TROUBLESHOOTING
TABLE 9-1: Boiler Troubleshooting Procedures
Fault Probable Causes
Incorrectly wired switch.
4.
Air/Fuel Valve unplugged.
1.
Loose wiring connection to the
2.
stepper motor.
Defective Air/Fuel Valve
3.
stepper motor.
STEPPER
Defective Power Supply Board
4.
MOTOR
or fuse.
FAILURE
Defective IGST Board.
5.
Air/Fuel Valve out of
6.
calibration

9.2 ADDITIONAL FAULTS WITHOUT SPECIFIC FAULT MESSAGES

Refer to Table 9-2 to troubleshoot faults which may occur without a specific fault message being
displayed.
TABLE 9-2: Boiler Troubleshooting with No Fault Message Displayed
Observed
Probable Causes
Incident
Clogged/damaged Gas
1.
Injector on Igniter-Injector
(Figure 8-1a through Figure 8-
1c).
Hard Light-
Defective Staged Ignition
2.
Off
Solenoid (Figure 8-1a through
Figure 8-1c).
Gas pressure going into unit is
1.
fluctuating.
Fluctuating
Damping Orifice not installed.
Gas 2.
Pressure
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Corrective Action
Ensure that the SSOV Proof of Closure switch
4.
is correctly wired.
Check that the Air/Fuel Valve is connected to
1.
the Edge [i] Controller.
Inspect for loose connections between the
2.
Air/Fuel Valve motor and the wiring harness.
Replace stepper motor.
3.
Check DS1 & DS2 LEDs on Power Supply
4.
Board. If they are not steady ON, replace
Power Supply Board.
Check "Heartbeat" LED DS1 and verify it is
5.
blinking ON & OFF every second. If not,
replace IGST Board.
Perform the stepper motor calibration
6.
Main Menu → Diagnostics →
procedure (
Subsystems → Air Fuel Valve Stepper
Corrective Action
Disconnect the Staged Ignition Assembly
1.
solenoid from the Gas injector Tube of the
Igniter-Injector (Figure 8-1a through Figure 8-
1c) and inspect Gas Injector to ensure it is not
clogged or damaged.
Close the Manual Shutoff Valve. Attempt to
2.
start the unit and listen for a "clicking" sound
that the Staged Ignition Solenoid makes
during Ignition Trial. If "clicking" sound is not
heard after 2 or 3 attempts, replace the
Staged Ignition Solenoid.
Stabilize gas pressure going into unit. If
1.
necessary, troubleshoot Building Supply
Regulator.
Check if the gas train is supposed to have a
2.
Damping Orifice, and if so, ensure that it is
installed in the SSOV Actuator, as shown in
Figure 10-1, below. For DBB Gas Trains, the
Damping Orifice is installed in the
.
Motor)
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