Benchmark 5000-6000 Operation & Maintenance Manual
SECTION 5
– TROUBLESHOOTING GUIDE
OMM-0118_B
•
GF-203
•
5/9/2019
Technical Support
•
(800) 526-0288
•
Mon-Fri, 8 am - 5 pm EST Page 71 of 148
TABLE 5-1: Boiler Troubleshooting Procedures
FAULT
INDICATION
PROBABLE CAUSES
CORRECTIVE ACTION
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 C-More Controller 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
COMMFAULT
1.
Unit not seeing information from Modbus
network.
1.
Check network connections. If fault persists, contact qualified
Service Personnel.
O2
PERCENTAGE
LOW
1.
Dirty air filter.
2.
Blockage in the inlet air duct.
3.
Gas pressure too high.
4.
Blocked flue.
5.
Blocked condensate trap.
6.
Blower failure
7.
VFD failure
1.
Remove air filter and clean per Section 4.10, above.
2.
Inspect all sections of the duct for foreign materials.
3.
Measure the gas pressure between the SSOV and the Air/Fuel
Valve.
It should be 7.9” W.C. ± 0.2” W.C. (2.0 kPa ± 50 Pa)
.
4.
Check flue for foreign material.
5.
Check condensate trap per Section 4.9, above.
6.
Check blower rotational speed with strobe light and compare to
VFD Hz output: RPM = 57.5 x Hz.
7.
Check VFD faceplate (available from AERCO after-market) using
the VFD manufacturer’s troubleshooting documentation.
O2 SENSOR
MALFUNCTION
1.
O
2
% reading <-4%, or >24%
1.
Check the O
2
offset and gain values in the Calibration menu. If set
to 1.0 and 1024 respectively, replace O
2
sensor
O2 % OUT OF
RANGE
1.
Combustion Calibration incorrect.
2.
Blocked inlet air duct or louver.
1.
Check Combustion Analyzer and recalibrate the boiler.
2.
Unblock air inlet and measure open area for combustion air to the
room.
OUTDOOR
TEMP SENSOR
FAULT
1.
Loose or broken wiring.
2.
Defective Sensor.
3.
Incorrect Sensor.
1.
Inspect Outdoor Temperature sensor for loose or broken wiring.
2.
Check resistance of sensor to determine if it is within specification.
3.
Ensure that the correct sensor is installed.
