Watts AERCO Benchmark BMK750 Operation And Service Manual page 149

Benchmark with Edge [I]: Operation-Maintenance Manual
SECTION 9 – TROUBLESHOOTING
TABLE 9-1: Boiler Troubleshooting Procedures
Fault Probable Causes
Worn Flame Detector or
1.
cracked ceramic.
Defective Regulator.
2.
FLAME
LOSS
DURING
Poor combustion calibration.
3.
RUN
Debris on burner.
4.
Blocked condensate drain.
5.
The Heat Demand Relays on
1.
the Ignition/Stepper (IGST)
HEAT
board failed to activate when
DEMAND
commanded.
FAILURE
Relay is activated when not in
2.
Demand.
Poor combustion calibration.
1.
HIGH
EXHAUST
TEMPERATU
Carboned heat exchanger due
2.
RE
to incorrect combustion
calibration.
Incorrect supply gas pressure.
1.
Defective SSOV Actuator.
2.
HIGH GAS
PRESSURE
Defective High Gas Pressure
3.
switch.
Faulty Water temperature
1.
HIGH
switch.
WATER
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9/18/2019
Corrective Action
Remove and inspect the Flame Detector for
1.
signs of wear or cracked ceramic. Replace if
necessary.
Check gas pressure readings using a gauge
2.
or manometer into and 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
3.
procedures in Section 4.4: Combustion
Calibration of this guide.
Remove the burner and inspect for any carbon
4.
build-up or debris. Clean and reinstall.
Remove blockage in condensate drain.
5.
Press CLEAR button and restart the unit. If
1.
the fault persists, replace Ignition/Stepper
(IGST) Board.
Defective relay. Replace IGST Board.
2.
Check combustion calibration using
1.
procedures in Section 4.4: Combustion
Calibration of this guide.
If exhaust temperature is greater than 200
2.
o
(93.3 C), check combustion calibration.
Calibrate or repair as necessary.
Check to ensure gas pressure at inlet of
1.
SSOV does not exceed 14" W.C. (3.49 kPa).
If gas supply pressure downstream of SSOV
2.
Actuator cannot be lowered to the range
specified in Table 4-1 (Natural Gas) or Table
4-4 (Propane) in Section 4.4: Combustion
Calibration of this guide; the SSOV Actuator
may be defective.
Remove the leads from the High Gas
3.
Pressure switch. Measure continuity across
the common (C) and normally closed (NC)
terminals with the unit not firing. Replace the
switch if continuity does not exist.
Test the temperature switch to insure it trips at
1.
its actual water temperature setting.
o
F
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