AERCO BMK 3.0 LN Nat. Gas APRIL 2009 - Manual (Page 59)

TROUBLESHOOTING
TABLE 8-1. BOILER TROUBLESHOOTING – Continued
FAULT INDICATION PROBABLE CAUSES CORRECTIVE ACTION
AIRFLOW FAULT
DURING PURGE
1. Blower not running or running too slow
2. Defective Air Flow Switch
3. Blocked Air flow Switch
4. Blocked Blower inlet or inlet ductwork.
5. No voltage to switch from control box.
6. No voltage to VFD.
7.
PROBABLE CAUSES
from 3 to 16
for AIRFLOW FAULT DURING
IGNITION applies for this fault
1. Start the unit. If the blower does not run check the blower solid
state relay for input and output voltage. If the relay is okay, check
the blower.
2. Start the unit. If the blower runs, check the airflow switch for
continuity. Replace the switch if there is no continuity.
3. Remove the air flow switch and inspect for signs of blockage,
clean or replace as necessary.
4. Inspect the inlet to the combustion blower including any ductwork
leading up to the combustion blower for signs of blockage.
5. Measure for 24 VAC during start sequence from each side of the
switch to ground. If 24VAC is not present refer to qualified
service personnel.
6. Check the fuses in the Power Box.
7. See
CORRECTIVE ACTION
from 3 to 16 for AIRFLOW
FAULT DURING IGNITION
AIRFLOW FAULT
DURING RUN
1. Blower stopped running due to thermal
or current overload
2. Blocked Blower inlet or inlet ductwork
3. Blocked airflow switch
4. Defective airflow switch
5. Combustion oscillations
6. PROBABLE CAUSES from 3 to 16
for AIRFLOW FAULT DURING
IGNITION applies for this fault
1. Check combustion blower for signs of excessive heat or high
current draw 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 airflow switch and inspect for signs of blockage,
clean or replace as necessary.
4. Measure the airflow 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. Run unit to full fire. If the unit rumbles or runs rough, perform
combustion calibration.
6.
PROBABLE CAUSES
from 3 to 16 for AIRFLOW FAULT
DURING IGNITION applies for this fault
8 -3