Benchmark 750-3000 Boiler Operation & Maintenance Manual
SECTION 5 – TROUBLESHOOTING GUIDE
OMM-0122_D
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GF-206
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5/9/2019
Technical Support
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(800) 526-0288
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Mon-Fri, 8 am - 5 pm EST Page 61 of 164
TABLE 5-1: Boiler Troubleshooting Procedures
Fault
Indication
Probable Causes
Corrective Action
AIRFLOW
FAULT
DURING
IGNITION
1.
Blower stopped running due to thermal or
current overload.
2.
Blocked Blower inlet or inlet air filter.
3.
Blockage in Blower Proof switch.
4.
Blockage in Blocked Inlet switch.
5.
Defective Blower Proof switch.
6.
Defective Blocked Inlet switch.
7.
Loose temperature to AUX connection in I/O
Box.
8.
Defective temperature sensor.
9.
Loose wire connection between the 0-10V
signal from I/O box to the Blower input.
10.
Defective I/O Box.
11.
Wrong 0-10V output selection on the C-More
Controller.
12.
Defective Air-Fuel Valve potentiometer.
13.
Hard light.
1.
Check combustion blower for signs of excessive heat or high current
drain that may trip thermal or current overload devices.
2.
Inspect the inlet to the combustion blower including the air filter at
the air/fuel valve for signs of blockage.
3.
Remove the Blower Proof switch and inspect for signs of blockage,
clean or replace as necessary.
4.
Remove the Blocked Inlet switch and inspect for signs of blockage,
clean or replace as necessary.
5.
Check the continuity of the Blower Proof switch with the combustion
blower running. If there is an erratic resistance reading or the
resistance reading is greater than zero ohms, replace the switch.
6.
Turn off unit and check the continuity of the Blocked Inlet switch. If
there is an erratic resistance reading or the resistance reading is
greater than zero ohms, replace the switch.
7.
Check the actual inlet air temperature and measure voltage at AUX
input in the I/O Box. Verify that the voltage conforms to the values
shown in Appendix C.
8.
Refer to CORRECTIVE ACTION 7 and verify that the voltage
conforms to the values shown in Appendix C.
9.
Check wire connection from I/O Box 0-10V signal to the Blower
Motor.
10.
Measure voltage at the I/O box 0-10V output. A voltage of 10V
equates to a 100% open valve position.
11.
Check the
Analog Out
option on the C-More
Configuration
menu.
Valve Position 0-10V
should be selected.
12.
Check Air/Fuel Valve position at 0%, 50% and 100% open
positions. The positions on the VALVE POSITION bargraph
should match the readings on the Air/Fuel Valve dial.
13.
Check igniter-injector for soot or erosion of electrode. Check
injector solenoid valve to insure proper open/close operation.
