AERCO BMK 2.0 LN Nat. Gas - Manual (Page 61)

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.