Watts AERCO Benchmark OMM-0121 Operation And Maintenance Manual page 61

Benchmark 750-3000 Boiler Operation & Maintenance Manual
SECTION 5 – TROUBLESHOOTING GUIDE
TABLE 5-1: Boiler Troubleshooting Procedures
Fault
Probable Causes
Indication
Blower stopped running due to thermal or
1.
current overload.
Blocked Blower inlet or inlet air filter.
2.
Blockage in Blower Proof switch.
3.
Blockage in Blocked Inlet switch.
4.
Defective Blower Proof switch.
5.
Defective Blocked Inlet switch.
6.
AIRFLOW
FAULT
Loose temperature to AUX connection in I/O
7.
DURING
Box.
IGNITION
Defective temperature sensor.
8.
Loose wire connection between the 0-10V
9.
signal from I/O box to the Blower input.
Defective I/O Box.
10.
Wrong 0-10V output selection on the C-More
11.
Controller.
Defective Air-Fuel Valve potentiometer.
12.
Hard light.
13.
OMM-0122_D • GF-206 • 5/9/2019 Technical Support • (800) 526-0288 • Mon-Fri, 8 am - 5 pm EST
Corrective Action
Check combustion blower for signs of excessive heat or high current
1.
drain that may trip thermal or current overload devices.
Inspect the inlet to the combustion blower including the air filter at
2.
the air/fuel valve for signs of blockage.
Remove the Blower Proof switch and inspect for signs of blockage,
3.
clean or replace as necessary.
Remove the Blocked Inlet switch and inspect for signs of blockage,
4.
clean or replace as necessary.
Check the continuity of the Blower Proof switch with the combustion
5.
blower running. If there is an erratic resistance reading or the
resistance reading is greater than zero ohms, replace the switch.
Turn off unit and check the continuity of the Blocked Inlet switch. If
6.
there is an erratic resistance reading or the resistance reading is
greater than zero ohms, replace the switch.
Check the actual inlet air temperature and measure voltage at AUX
7.
input in the I/O Box. Verify that the voltage conforms to the values
shown in Appendix C.
Refer to CORRECTIVE ACTION 7 and verify that the voltage
8.
conforms to the values shown in Appendix C.
9. Check wire connection from I/O Box 0-10V signal to the Blower
Motor.
Measure voltage at the I/O box 0-10V output. A voltage of 10V
10.
equates to a 100% open valve position.
Check the Analog Out option on the C-More Configuration menu.
11.
Valve Position 0-10V should be selected.
Check Air/Fuel Valve position at 0%, 50% and 100% open
12.
positions. The positions on the VALVE POSITION bargraph
should match the readings on the Air/Fuel Valve dial.
Check igniter-injector for soot or erosion of electrode. Check
13.
injector solenoid valve to insure proper open/close operation.
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