AERCO BMK 3.0 LN Dual-Fuel Series Gas Fired Low NOx Boiler System - Manual (Page 68)

TROUBLESHOOTING
8-6
TABLE 8-1. BOILER TROUBLESHOOTING – Continued
FAULT INDICATION PROBABLE CAUSES CORRECTIVE ACTION
(continued) 3. Defective High Gas Pressure Switch
4. Gas pressure snubber not installed.
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.
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. Boiler Management System PID or other
settings not correctly setup.
7. No interlock to boiler or BMS to disable
boiler(s) in event that system pumps
have failed.
8. System flow rate changes are occurring
faster than boilers 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 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.
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.