OMM-0153_E
• 5/11/2023 Technical Support • (800) 526-0288 • Mon-Fri, 8 am - 5 pm EST Page 102 of 124
CENTURION Installation, Operation & Maintenance Manual
SECTION 10: TROUBLESHOOTING
Centurion Troubleshooting Procedures
Fault
Probable Causes
Corrective Action
2.
Relay is activated when not
in Demand.
2.
Defective relay. Replace IGST Board.
HIGH EXHAUST
TEMPERATURE
1.
Poor combustion calibration.
1.
Check combustion calibration using procedures in
Section 5.4:
Combustion Calibration
of this
guide.
2.
Carboned heat exchanger
due to incorrect combustion
calibration.
2.
If exhaust temperature is greater than 200°F
(93.3°C), check combustion calibration. Calibrate or
repair as necessary.
HIGH GAS
PRESSURE
1.
Incorrect supply gas
pressure.
1.
Check to ensure gas pressure at inlet of SSOV does
not exceed 14” W.C. (3.49 kPa).
2.
Defective SSOV Actuator.
2.
If gas supply pressure downstream of SSOV Actuator
cannot be lowered to
below 2.5” W.C. (622 Pa)
; the
SSOV Actuator may be defective.
3.
Defective High Gas Pressure
switch.
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.
1.
Test the temperature switch to insure it trips at its
actual water temperature setting.
2.
Incorrect PID settings.
2.
Check PID settings (Advanced Setup
→
Performance
→
Temperature Control, first 3 items). If the settings
have been changed, record the current readings
then reset to default values.
3.
Faulty shell temperature
sensor.
3.
Using the resistance charts in Appendix B:
Temperature Sensor Resistance/Voltage Chart
measure the resistance of Shell sensor and BTU
sensor at a known water temperature.
4.
Unit in Manual mode.
4.
If unit is in Manual mode, switch to Auto mode
(Diagnostic
→
Manual Run, Manual Mode).
5.
Unit setpoint is greater than
Over Temperature switch
setpoint.
5.
Check setpoint of unit and setpoint of Temperature
switch; Ensure that the temperature switch is set
higher than the unit’s setpoint.
6.
System flow rate changes
are occurring faster than
units can respond.
6.
If 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.
1.
See High Water Temperature Switch Open.
2.
Temp HI Limit setting is too
low.
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.
2.
32 Pin Ribbon cable
defective.
2.
Replace 32 Pin Ribbon cable.
