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 68 of 148
TABLE 5-1: Boiler Troubleshooting Procedures
FAULT
INDICATION
PROBABLE CAUSES
CORRECTIVE ACTION
GAS
PRESSURE
FAULT
(Due to High
Gas Pressure)
1.
Incorrect supply gas pressure.
2.
Defective SSOV Actuator.
3.
Defective High Gas Pressure switch.
1.
Check to ensure gas pressure at inlet of SSOV does not
exceed
14” W.C. (3487 Pa)
2.
If NATURAL GAS supply pressure downstream of SSOV Actuator
cannot be lowered using the gas pressure adjustment screw to the
range specified in the
Benchmark 5000
– 6000 Installation and
Startup Guide,
OMM-0117 (GF-202), Section 4.5.1, Table 4-1
(Natural Gas) or Section 4.5.2, Table 4-4 (Propane), the SSOV
Actuator may be defective.
3.
Remove the leads from the High Gas Pressure switch. Measure
continuity across the common (C) and normally closed (NC)
terminals with the unit not firing. Replace the switch if continuity
does not exist.
HIGH WATER
TEMP
SWITCH OPEN
1.
Faulty Water temperature switch.
2.
Incorrect PID settings.
3.
Faulty shell temperature sensor.
4.
Unit in MANUAL mode.
5.
Unit setpoint is greater than Over Temperature
switch setpoint.
6.
System flow rate changes are occurring faster
than units can respond.
7.
Refractory failure.
8.
VFD is in “Local” mode, or voltage dropped
below threshold.
1.
Test the temperature switch to insure it trips at its actual water
temperature setting.
2.
Check PID settings against menu default settings in Section 2,
above. If the settings have been changed, record the current
readings then reset them to the default values.
3.
Using the resistance charts in the Appendix C, Measure the
resistance of Shell sensor and BTU sensor at a known water
temperature.
4.
If unit is in MANUAL mode, switch to AUTO mode.
5.
Check setpoint of unit and setpoint of Temperature switch; Ensure
that the temperature switch is set higher than the unit’s setpoint.
6.
If the system is a variable flow system, monitor system flow
changes to ensure that the rate of flow change is not faster than
what the units can respond to.
7.
Refractory temperature switches on the end plates are in series
with the water temperature limit control to shut down the boiler if
the end plates get too hot. Replace the refractory at the hottest end
plate.
8.
Check incom
ing voltage, set VFD to “Remote” mode.
