AERCO BMK 3.0 LN Nat. Gas Jan 2011 User 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.

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

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.

PROBABLE CAUSES

f rom 3 to 12 for AIRFLOW FAULT

DURING IGNITION

applies for this fault