AERCO BMK 2.0 LN Nat. Gas for Mass. only - Manual (Page 64)

TROUBLESHOOTING
8 -10
TABLE 8-1. BOILER TROUBLESHOOTING – Continued
FAULT INDICATION PROBABLE CAUSES TROUBLESHOOTING/CORRECTIVE ACTION
(continued) 2. Defective Flame Detector 2. Replace Flame Detector.
SSOV FAULT
DURING PURGE
3. 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.
4. Defective Air/Fuel Valve stepper
motor.
5. Defective Power Supply Board or
fuse
6. Defective IGST Board
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.
4. Replace stepper motor.
5. Check DS1 & DS2 LEDs on Power Supply Board. If they are not
steady ON, replace Power Supply Board.
6. Check “Heartbeat” LED DS1 and verify it is blinking ON & OFF
every second. If not, replace IGST Board.