AERCO BMK 6000 - Manual (Page 120)

Benchmark 6000 Boiler Installation, Operation & Maintenance Manual
CHAPTER 8 – TROUBLESHOOTING GUIDE
Page 120 of 210
AERCO International, Inc. • 100 Oritani Dr. • Blauvelt, NY 10913
OMM-0086_0D
03/20/14
Ph.: 800-526-0288
GF-133
TABLE 8-1: BOILER TROUBLESHOOTING – Continued
FAULT INDICATION PROBABLE CAUSES CORRECTIVE ACTION
O2 PERCENTAGE LOW
1. Dirty air filter..
2. Blockage in the inlet air duct.
3. Gas pressure too high.
4. Blocked flue.
5. Blocked condensate trap.
6. Blower failure
7. VFD failure
1. Remove air filter and clean per section 7.9.
2. Inspect all sections of the duct for foreign materials.
3. Measure the gas pressure between the SSOV and the Air/Fuel
Valve. Pressure should be 7.9” W.C. ± 0.2” W.C.
4. Check flue for foreign material. Measure pressure at exhaust
manifold and compare to pressure map (Figure 8-1).
5. Check condensate trap per section 7.8.
6. Check blower rotational speed with strobe light and compare to
VFD Hz output: RPM = 57.5 x Hz.
7. Check VFD faceplate (available from AERCO after-market) using
the VFD manufacturer’s troubleshooting documentation.
O2 SENSOR
MALFUNCTION 1. O
2
% reading <-4%, or >24% 1. Check the O
2
offset and gain values in the Calibration menu. If
set to 1.0 and 1024 respectively, replace O
2
sensor
O2 % OUT OF RANGE
1. Combustion Calibration incorrect.
2. Blocked inlet air duct.
1. Check Combustion Analyzer and recalibrate boiler.
2. Unblock inlet & measure open area for combustion air to room.
OUTDOOR TEMP
SENSOR FAULT
1. Loose or broken wiring.
2. Defective Sensor.
3. Incorrect Sensor.
1. Inspect Outdoor Temperature sensor for loose or broken wiring.
2. Check resistance of sensor to determine if it is within
specification.
3. Ensure that the correct sensor is installed.
PRG SWTCH CLOSED
DURING IGNITION
1. A/F Valve rotated open to purge
and did not rotate to ignition
position.
2. Defective or shorted switch.
3. Switch wired incorrectly.
1. Start the unit. The Air/Fuel Valve should rotate to the purge
(open) position, then back to ignition position (towards closed)
during the ignition cycle. If the valve does not rotate back to the
ignition position, check the Air/Fuel Valve calibration. If
calibration is okay, the problem may be in the Air/Fuel Valve or
the Control Box. Refer fault to qualified service personnel.
2. If the Air/Fuel Valve does rotate to the ignition position, check the
purge switch for continuity between the N.O. and COM terminals.
If the switch shows continuity when not in contact with the cam,
check to ensure that the switch is wired correctly (correct wire
numbers on the normally open terminals).
3. If the switch is wired correctly, replace the switch.