Watts AERCO Benchmark OMM-0121 Operation And Maintenance Manual page 64

Benchmark 750-3000 Boiler Operation & Maintenance Manual
SECTION 5 – TROUBLESHOOTING GUIDE
TABLE 5-1: Boiler Troubleshooting Procedures
Fault
Probable Causes
Indication
Worn Flame Detector or cracked ceramic.
1.
Defective Regulator.
2.
FLAME LOSS
Poor combustion calibration.
3.
DURING RUN
Debris on burner.
4.
5. Blocked condensate drain.
The Heat Demand Relays on the
1.
Ignition/Stepper (IGST) board failed to activate
HEAT DEMAND
when commanded.
FAILURE
Relay is activated when not in Demand.
2.
Poor combustion calibration.
1.
HIGH EXHAUST
TEMPERATURE
Carboned heat exchanger due to incorrect
2.
combustion calibration.
Incorrect supply gas pressure.
1.
Defective SSOV Actuator.
2.
HIGH GAS
PRESSURE
Defective High Gas Pressure switch.
3.
OMM-0122_D • GF-206 • 5/9/2019 Technical Support • (800) 526-0288 • Mon-Fri, 8 am - 5 pm EST
Corrective Action
Remove and inspect the Flame Detector for signs of wear or
1.
cracked ceramic. Replace if necessary.
Check gas pressure readings using a gauge or manometer into and
2.
out of the Air/Fuel Valve to ensure that the gas pressure into and
out of the valve is correct.
Check combustion calibration using the procedures in Section 4.4 of
3.
the Benchmark 750 – 3000 Installation and Startup Guide, OMM-
0121 (GF-205).
Remove the burner and inspect for any carbon build-up or debris.
4.
Clean and reinstall.
Remove blockage in condensate drain.
5.
Press CLEAR button and restart the unit. If the fault persists,
1.
replace Ignition/Stepper (IGST) Board.
Defective relay. Replace IGST Board.
2.
Check combustion calibration using procedures in Section 4.4 of the
1.
Benchmark 750 – 3000 Installation and Startup Guide, OMM-0121
(GF-205).
If exhaust temperature is greater than 200
2.
combustion calibration. Calibrate or repair as necessary.
Check to ensure gas pressure at inlet of SSOV does not exceed
1.
14" W.C. (3.49 kPa).
If gas supply pressure downstream of SSOV Actuator cannot be
2.
lowered to the range specified in Table 4-1 (Natural Gas) or Table
4-4 (Propane) in Section 4.4 of the Benchmark 750 – 3000
Installation and Startup Guide, OMM-0121 (GF-205), the SSOV
Actuator may be defective.
Remove the leads from the High Gas Pressure switch. Measure
3.
continuity across the common (C) and normally closed (NC)
terminals with the unit not firing. Replace the switch if continuity
does not exist.
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