Watts AERCO Benchmark OMM-0121 Operation And Maintenance Manual page 68

Benchmark 750-3000 Boiler Operation & Maintenance Manual
SECTION 5 – TROUBLESHOOTING GUIDE
TABLE 5-1: Boiler Troubleshooting Procedures
Fault
Probable Causes
Indication
A/F Valve rotated open to purge and did not
1.
rotate to ignition position.
PRG SWTCH
Defective or shorted switch.
2.
CLOSED
DURING
IGNITION
Switch wired incorrectly.
3.
Defective Power Supply Board or fuse.
4.
Defective IGST Board.
5.
Defective Purge switch.
1.
No voltage present at switch.
2.
PRG SWTCH
OPEN
Switch wired incorrectly.
3.
DURING
PURGE
Defective Power Supply Board or fuse
4.
5. Defective IGST Board.
OUTDOOR Loose or broken wiring.
1.
TEMP
Defective Sensor.
2.
SENSOR
Incorrect Sensor.
3.
FAULT
OMM-0122_D • GF-206 • 5/9/2019 Technical Support • (800) 526-0288 • Mon-Fri, 8 am - 5 pm EST
Corrective Action
Start the unit. The Air/Fuel Valve should rotate to the purge (open)
1.
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 C-More Controller.
Refer fault to qualified service personnel.
If the Air/Fuel Valve does rotate to the ignition position, check the
2.
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).
If the switch is wired correctly, replace the switch.
3.
Check DS1 & DS2 LEDs on Power Supply Board. If they are not
4.
steady ON, replace Power Supply Board.
Check "Heartbeat" LED DS1 and verify it is blinking ON & OFF
5.
every second. If not, replace IGST Board.
If the air-fuel valve does rotate, check Purge switch for continuity
1.
when closing. Replace switch if continuity does not exist.
Measure for 24 VAC from each side of the switch to ground. If
2.
24VAC is not present, refer fault to qualified service personnel.
Check to ensure that the switch is wired correctly (correct wire
3.
numbers on the normally open terminals).
Check DS1 & DS2 LEDs on Power Supply Board. If they are not
4.
steady ON, replace Power Supply Board.
Check "Heartbeat" LED DS1 and verify it is blinking ON & OFF
5.
every second. If not, replace IGST Board.
Inspect Outdoor Temperature sensor for loose or broken wiring.
1.
Check resistance of sensor to determine if it is within specification.
2.
Ensure that the correct sensor is installed.
3.
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