Aerco BENCHMARK 2500DF User Manual page 109

Benchmark 2500DF-3000DF Installation, Operation & Maintenance Manual
FAULT INDICATION
HIGH GAS
PRESSURE
HIGH WATER TEMP
SWITCH OPEN
HIGH WATER
TEMPERATURE
IGN BOARD
COMM FAULT
OMM-0099_0A
GF-145
CHAPTER 8 – TROUBLESHOOTING GUIDE
TABLE 8-1: BOILER TROUBLESHOOTING – Continued
PROBABLE CAUSES
1. Incorrect supply gas pressure.
2. Defective SSOV Actuator.
3. Defective High Gas Pressure Switch.
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. See HIGH WATER TEMPERATURE
SWITCH OPEN.
2. Temp HI Limit setting is too low.
1. Communication fault has occurred
between the PMC board and
Ignition/Stepper (IGST) board
AERCO International, Inc. • 100 Oritani Dr. • Blauvelt, NY 10913
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 following values using the gas pressure adjustment screw (see section
4.3 or 4.4, step 9), the SSOV Actuator may be defective:
• BMK3000DF = 6.0" ± 0.2" W.C. for Natural Gas or 1.6" ± 0.2" W.C. for
Propane Gas.
• BMK2500DF = 6.0" ± 0.2" W.C. for Natural Gas or 2.0" ± 0.2" W.C. for
Propane Gas.
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.
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.
1. See HIGH WATER TEMPERATURE SWITCH OPEN.
2. Check Temp HI Limit setting.
1. Press CLEAR button and restart unit. If fault persists, contact qualified
Service Personnel.
Ph.: 800-526-0288
CORRECTIVE ACTION
Page 109 of 234
PR1: 05/21/2014