Watts AERCO Benchmark 2.0LN, Operating & Maintenance Instructions

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TROUBLESHOOTING
8-9
TABLE 8-1. BOILER TROUBLESHOOTING – Continued
FAULT INDICATION PROBABLE CAUSES CORRECTIVE ACTION
continued 3. Control Box signal type
selection switches not set for
correct signal type (voltage or
current).
1. Check DIP switch on PMC board to ensure it is set correctly for the type of
signal being sent. Check control signal type set in Configuration Menu.
RESIDUAL
FLAME
1. SSOV not fully closed.
2. Defective Flame Detector.
1. Check open/close indicator window of Safety Shut-Off Valve (SSOV) and
ensure that the SSOV is fully closed. If not fully closed, replace the valve and
or actuator.
Close gas shut-off valve downstream of SSOV. Install a manometer or gauge
in a gas test port between the SSOV and the gas shut off valve. If a gas
pressure reading is observed replace the SSOV valve and or actuator.
2. Replace Flame Detector.
SSOV FAULT
DURING PURGE
See SSOV SWITCH OPEN
SSOV FAULT
DURING RUN
1. SSOV switch closed for 15
seconds during run.
1. Replace or adjust microswitch in SSOV actuator. If fault persists, replace
actuator.
SSOV RELAY
FAILURE
1. SSOV relay failed on board. 1. Press CLEAR button and restart unit. If fault persists, replace
Ignition/Stepper (IGST) Board.
SSOV
SWITCH OPEN
1. Actuator not allowing for full
closure of gas valve
2. SSOV powered when it should
not be
3. Defective Switch or Actuator
4. Incorrectly wired switch.
1. Observe operation of the Safety Shut-Off Valve (SSOV) through indicator on
the Valve actuator and ensure that the valve is fully and not partially closing.
2. If the SSOV never closes, it may be powered continuously. Close the gas
supply and remove power from the unit. Refer fault to qualified service
personnel.
3. Remove the electrical cover from the SSOV and check switch continuity. If
the switch does not show continuity with the gas valve closed, either adjust
or replace the switch or actuator.
4. Ensure that the SSOV Proof of Closure switch is correctly wired.
STEPPER MOTOR
FAILURE
1. Air/Fuel Valve out of calibration.
2. Air/Fuel Valve unplugged.
3. Loose wiring connection to the
stepper motor.
1. Refer to GF-112 and perform Stepper Test (para. 6.3.5) to ensure stepper
motor rotates properly between the 0% (fully closed) and 100% (fully open)
positions. Verify that the FIRE RATE bargraph and the dial on the Air/Fuel
Valve track each other to indicate proper operation. If operation is not
correct, perform the Stepper Feedback Calibration (GF-112, para. 6.2.1).
2. Check that the Air/Fuel Valve is connected to the Control Box.
3. .Inspect for loose connections between the Air/Fuel Valve motor and the
wiring harness.