Instruction Manual

Benchmark 750/1000 Boiler Installation, Operation & Maintenance Manual
CHAPTER 8 – TROUBLESHOOTING GUIDE
OMM-0082_0J AERCO International, Inc. • 100 Oritani Dr. • Blauvelt, NY 10913 Page 107 of 192
GF-130 Ph.: 800-526-0288 05/21/2014
TABLE 8-1. BOILER TROUBLESHOOTING – Continued
FAULT INDICATION
PROBABLE CAUSES
CORRECTIVE ACTION
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.
2. If gas supply pressure downstream of SSOV Actuator
cannot be lowered to the range of 2.0” ± 0.4” W.C. using
the gas pressure adjustment screw (see section 4.3, step
10), 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.
1. Test the temperature switch to insure it trips at its actual
water temperature setting.
2. Check PID settings against Menu Default settings in
Appendix E. 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.
HIGH WATER
TEMPERATURE
1. See HIGH WATER
TEMPERATURE SWITCH OPEN.
2. Temp HI Limit setting is too low.
1. See HIGH WATER TEMPERATURE SWITCH OPEN.
2. Check Temp HI Limit setting.
IGN BOARD
COMM FAULT
1. Communication fault has occurred
between the PMC board and
Ignition/Stepper (IGST) board
1. Press CLEAR button and restart unit. If fault persists,
contact qualified Service Personnel.