AERCO BMK 1.5 LN July 2011 - Manual (Page 90)

CHAPTER 7: MAINTENANCE
Page 90 of 152 PR2: 05/09/12
Benchmark 1.5LN Low NOx Boiler
Operation and Maintenance Manual
OMM-0041_0D
GF-120
AERCO International, Inc. • 100 Oritani Dr. • Blauvelt, NY 10913 • Ph: 800-526-0288
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 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 SSOV Actuator(s) with the unit
firing. For FM gas trains, ensure it is between 4.0” W.C. and 2 psig. For
IRI gas trains, ensure it is between 4.2" W.C. and 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 seeing 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. The Air/Fuel Valve should rotate to the purge (open)
position, then back to ignition position (towards closed) during the ignition
cycle. If the valve does not rotate back to the ignition position, check the
Air/Fuel Valve calibration. If calibration is okay, the problem may be in
the Air/Fuel Valve or the Control Box. Refer fault to qualified service
personnel.