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TROUBLESHOOTING
TABLE 8-1. BOILER TROUBLESHOOTING – Continued
FAULT INDICATION
(continued)
7. Defective Differential Pressure
8. Carbon or other debris on Burner
FLAME LOSS
1. Worn Flame Detector or cracked
DURING RUN
2. Defective Differential Regulator.
3. Poor combustion calibration.
4. Debris on burner.
5. Blocked condensate drain.
HEAT DEMAND
1. The Heat Demand Relays on the
FAILURE
2. Relay is activated when not in
HIGH EXHAUST
1. Defective exhaust sensor.
TEMPERATURE
2. Carboned heat exchanger due to
HIGH GAS
1. Incorrect supply gas pressure.
PRESSURE
2. Defective SSOV Supply Regulator.
-4
8
PROBABLE CAUSES
Regulator
ceramic.
Ignition/Stepper board failed to
activate when commanded
Demand
incorrect combustion calibration
CORRECTIVE ACTION
7. Check gas pressure readings using gauge or manometer into
and out of the Air/Fuel Valve to ensure gas is getting to the
burner.
8. Remove the burner and inspect for any carbon or debris. Clean
and reinstall
1. Remove and inspect the Flame Detector for signs of wear or
cracked ceramic. Replace if necessary.
2. Check gas pressure readings using a gauge or manometer into
and out of the Air/Fuel Valve to ensure that the gas pressure
into and out of the valve is correct.
3. Check combustion calibration. Adjust as necessary.
4. Remove the burner and inspect for any carbon or debris. Clean
and reinstall.
5. Remove blockage in condensate drain.
1. Press CLEAR button and restart the unit. If the fault persists,
replace Ignition/Stepper (IGST) Board.
2. Defective relay. Replace IGST Board.
1. Measure the actual exhaust temperature and continuity of the
exhaust sensor. If the exhaust temperature is less than 475
and the exhaust sensor shows continuity replace the sensor.
2. If exhaust temperature is greater than 500
combustion calibration. Calibrate or repair as necessary.
1. Check to ensure gas pressure at inlet of SSOV is 2 psig
maximum.
2. If gas supply pressure downstream of SSOV cannot be
lowered, to 4.8" W.C. (see para. 4.3, step 8), the SSOV Supply
Regulator may be defective. For Benchmark 2.0 Low NOx
boilers configured for De-Rated capacity (see para. 2.4.1), if
gas supply pressure downstream of the SSOV cannot be
lowered to
o
F
o
F, check
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