AERCO BMK 1.5 LN July 2011 - Manual (Page 92)

CHAPTER 7: MAINTENANCE
Page 92 of 152 PR2: 05/09/12
Benchmark 1.5LN Low NOx Boiler
Operation and Maintenance Manual
OMM-0041_0D
GF-120
AERCO International, Inc. • 100 Oritani Dr. • Blauvelt, NY 10913 • Ph: 800-526-0288
TABLE 8-1. BOILER TROUBLESHOOTING (Continued)
FAULT
INDICATION
PROBABLE CAUSES CORRECTIVE ACTION
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.
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.
2. Floating Neutral.
3. Hot and Neutral reversed at SSOV.
1. Press CLEAR button and restart unit. If fault persists, replace Ignition/Stepper
(IGST) Board.
2. The Neutral and Earth Ground are not connected at the source and therefore
there is a voltage measured between the two. Normally this measurement should
be near zero or no more than a few millivolts.
3. Check SSOV power wiring.
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.
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 VALVE POSITION 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).