CHAPTER 8: TROUBLESHOOTING GUIDE
Page
90
of
158
PR2: 04/22/13
Benchmark 2.0LN Dual-Fuel Low NOx Boiler
Operation and Maintenance Manual
OMM-0052_0E
GF-127
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 supply gas regulator with the unit
firing. Refer to paragraph 2.7.1 to ensure that the gas pressure is correct
for the type of fuel and gas train being used.
2. Measure gas pressure at the low gas pressure switch. If it is greater than
2.6” W.C. (or 2.1"W.C. for propane), 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.
