AERCO BMK 3.0 LN Nat. Gas Jan 2011 - Manual (Page 61)

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. PROBABLE CAUSES from 3 to 12
for AIRFLOW FAULT DURING
IGNITION
also apply for this fault
1. Start the unit. If the blow er does not r un check the blow er solid
state relay for input and output voltage. If the relay is okay, check
the blower.
2. Start the unit. If the blow er r uns, c heck the airflow switch for
continuity. Replace the switch if there is no continuity.
3. Remove the air flow s witch and ins pect f or s igns of bloc kage,
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 gr ound. If 24VAC is not present refer to qualified
service personnel.
6. See CORRECTIVE ACTION f rom 3 to 12 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 12
for AIRFLOW FAULT DURING
IGNITION
applies for this fault
1. Check combustion blower for s igns of ex cessive 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 c ombustion blow er f or s igns of blockage.
3. Remove the air flow s witch and ins pect for signs of blockage,
clean or replace as necessary.
4. Measure the air flow s witch f or c ontinuity with the combustion
blower running. If ther e is an er ratic r esistance r eading or the
resistance reading is greater than zero ohms, replace the switch.
5. Run unit to f ull f ire. If the unit r umbles or r uns r ough, per form
combustion calibration.
6. PROBABLE CAUSES f rom 3 to 12 for AIRFLOW FAULT
DURING IGNITION
applies for this fault
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