TROUBLESHOOTING
TABLE 8-1. BOILER TROUBLESHOOTING
FAULT INDICATION PROBABLE CAUSES TROUBLESHOOTING/CORRECTIVE ACTION
AIRFLOW FAULT
DURING IGNITION
1. Blower stopped running due to thermal
or current overload
2. Blocked Blower inlet or inlet ductwork
3. Blocked Blower proof switch
4. Defective Blower proof switch
5. Blockage in blocked-air inlet switch
6. Defective blocked air inlet switch
7. Loose temperature sensor 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 Motor input
10. Defective I/O box
11. Wrong 0-10V output selection on the
control box
12. Defective Air-Fuel Valve
potentiometer
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 any ductwork
leading up to the combustion blower for signs of blockage.
3. Remove the Blower proof switch and inspect for signs of
blockage, clean or replace as necessary.
4. Measure the Blower proof switch for continuity with the
combustion blower running. If there is an erratic resistance
reading or the resistance reading is greater than zero ohms,
replace the switch.
5. Remove the blocked air inlet switch and inspect for signs of
blockage, clean or replace as necessary.
6. Measure the blocked-air inlet switch for continuity with the
combustion blower running. 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 the tabular listing provided 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 8.2V
equates to a 100% open Air/Fuel 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% valve
positions, the position on the C-More barograph should match
the valve position.
8-2
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