Watts AERCO Benchmark OMM-0121 Operation And Maintenance Manual page 62

Benchmark 750-3000 Boiler Operation & Maintenance Manual
SECTION 5 – TROUBLESHOOTING GUIDE
TABLE 5-1: Boiler Troubleshooting Procedures
Fault
Probable Causes
Indication
Blower not running or running too slow.
1.
Defective Blocked Inlet switch.
2.
Blockage in air filter or Blocked Inlet switch.
AIRFLOW 3.
FAULT
DURING
Blocked blower inlet or inlet ductwork.
4.
PURGE
No voltage to Blocked Inlet switch from C-More
5.
Controller.
PROBABLE CAUSES from 3 to 12 for
6.
AIRFLOW FAULT DURING IGNITION apply for
this fault.
Blower stopped running due to thermal or
1.
current overload.
Blocked Blower inlet or inlet ductwork.
2.
Blockage in air filter or Blocked Inlet switch.
3.
AIRFLOW
FAULT
Defective Blocked Inlet switch.
4.
DURING RUN
Combustion oscillations.
5.
Probable causes from 3 to 16 for AIRFLOW
6.
FAULT DURING IGNITION applies for this fault.
OMM-0122_D • GF-206 • 5/9/2019 Technical Support • (800) 526-0288 • Mon-Fri, 8 am - 5 pm EST
Corrective Action
Start the unit. If the blower does not run check the blower solid state
1.
relay for input and output voltage. If the relay is OK, check the
blower.
Start the unit. If the blower runs, turn off unit and check the Blocked
2.
Inlet switch for continuity. Replace the switch if continuity does not
exist.
Remove the air filter and Blocked Inlet switch and inspect for signs
3.
of blockage. Clean or replace as necessary.
Inspect the inlet to the combustion blower including any ductwork
4.
leading up to the combustion blower for signs of blockage.
During the start sequence, verify that 24 VAC is present between
5.
each side of the switch and ground. If 24 VAC is not present, refer
fault to qualified service personnel.
See CORRECTIVE ACTIONS from 3 to 12 for AIRFLOW FAULT
6.
DURING IGNITION.
Check combustion blower for signs of excessive heat or high
1.
current draw that may trip thermal or current overload devices.
Inspect the inlet to the combustion blower, including any ductwork
2.
leading up to the combustion blower, for signs of blockage.
Remove the air filter and Blocked Inlet switch and inspect for signs
3.
of blockage, clean or replace as necessary.
4. Verify that 24 VAC is present between each side of the switch and
ground. If 24 VAC is not present at both sides, replace switch.
Run unit to full fire. If the unit rumbles or runs rough, perform
5.
combustion calibration.
See CORRECTIVE ACTIONS from 3 to 12 for AIRFLOW FAULT
6.
DURING IGNITION.
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