AERCO BMK 3.0 LN Nat. Gas Jan 2011 - Manual (Page 66)

TROUBLESHOOTING
TABLE 8-1. BOILER TROUBLESHOOTING – Continued
FAULT INDICATION PROBABLE CAUSES CORRECTIVE ACTION
INTERLOCK
OPEN
1. Interlock jumper not installed or
removed
2. Energy Management System does
not have boiler enabled.
3. Device proving switch hooked to
interlocks is not closed.
1. Check for a jumper properly installed across the interlock
terminals in the I/O box
2. If there are two external wires on these terminals check any
Energy Management system to see if they have the units
disabled (a jumper may be temporarily installed to see if the
interlock circuit is functioning).
3. Check that proving switch for any device hooked to the interlock
circuit is closing and that the device is operational.
LINE VOLTAGE
OUT OF PHASE
1. Line and Neutral switched in AC
Power Box.
2. Incorrect power supply transformer
wiring.
1. Check Line (hot) and Neutral in AC Power Box to ensure they
are not reversed
2. Check transformer wiring, in AC Power Box, against the power
box transformer wiring diagram to ensure it is wired correctly
LOW GAS
PRESSURE
1. Incorrect supply gas pressure.
2. Defective Low Pressure Gas Switch
1. Measure gas pressure upstream of the supply gas regulator with
the unit firing. Ensure it is at least 3.5” W.C. for FM gas train, or
4.0” W.C. for IRI gas train. Max. allowable pressure is 2 psig
(see para. 2.7.1).
2. Measure gas pressure at the low gas pressure switch. If it is
greater than 2.6” W.C., measure continuity across the switch and
replace if necessary.
LOW WATER
LEVEL
1. Insufficient water level in system
2. Defective water level circuitry.
3. Defective water level probe.
1. Check system for sufficient water level.
2. Test water level circuitry using the Control Box front panel LOW
WATER TEST and RESET buttons. Replace water level
circuitry if it does not respond.
3. Check continuity of probe end to the shell, change probe if there
is no continuity.
MODBUS COMM
FAULT
1. Boiler not s eeing information from
Modbus network
1. Check network connections. If fault persists, contact qualified
Service Personnel.
PRG SWTCH CLOSED
DURING IGNITION
1. A/F Valve rotated open to purge and
did not rotate to ignition position
1. Start the unit. T he Air /Fuel Valve s hould r otate to the pur ge
(open) position, then back to ignition pos ition ( towards c losed)
during the ignition c ycle. If the valve does not rotate back to the
ignition position, c heck the Air /Fuel Valve c alibration. If
calibration is okay, the pr oblem may be in the Air /Fuel Valve or
the Control Box. Refer fault to qualified service personnel.
8 - 8