High Water Temp Switch Open; High Water Temperature; Ign Board Comm Fault - Aerco Benchmark 2.0 Installation, Operation & Maintenance Instructions Manual

TROUBLESHOOTING
TABLE 8-1. BOILER TROUBLESHOOTING – Continued
FAULT INDICATION
(continued) 3. Defective High Gas Pressure Switch
4. Gas pressure snubber not installed.
5. Fluctuating supply gas pressure.
HIGH WATER TEMP 1. Faulty Water temperature switch.
SWITCH OPEN
2. Incorrect PID settings.
3. Faulty shell temperature sensor.
4. Unit in Manual mode
5. Unit setpoint is greater than Over
6. Boiler Management System PID or
7. No interlock to boiler or BMS to
8. System flow rate changes are
HIGH WATER 1. See HIGH WATER TEMPERATURE
TEMPERATURE
2. Temp HI Limit setting is too low.
IGN BOARD 1. Communication fault has occurred
COMM FAULT
-
8 6
PROBABLE CAUSES
Temperature Switch setpoint.
other settings not correctly setup.
disable boiler(s) in event that system
pumps have failed.
occurring faster than boilers can
respond.
SWITCH OPEN.
between the PMC board and
Ignition/Stepper (IGST) board
TROUBLESHOOTING/CORRECTIVE ACTION
3. Remove the leads from the high gas pressure switch and
measure continuity across the common and normally closed
terminals with the unit not firing. Replace the switch if it does not
show continuity.
4. See Figure 8-1. Ensure that the gas pressure snubber is installed
at the high gas pressure switch.
5. Measure gas pressure upstream of SSOV and monitor for
sudden changes (see Fig. 8-1).
1. Test the temperature switch to insure it trips at its actual water
temperature setting.
2. Check PID settings against Menu Default settings in the
Appendix. 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. Check the BMS for changes to PID default values, correct as
necessary.
7. If system pump is controlled by Energy Management System
other than BMS or pumps are individually controlled by boiler,
check to see if there are flow switches interlocked to the BMS or
boiler.
8. 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 boilers 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.