AERCO KC1000 Heater 2002 - Manual (Page 67)

TROUBLESHOOTING
7-5
KC1000 WATER HEATER TROUBLESHOOTING TABLE – Continued
FAULT INDICATION PROBABLE CAUSES CORRECTIVE ACTION
(continued) 3. Defective High Gas Pressure Switch 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.
HIGH WATER TEMP
SWITCH OPEN
1. Scaled BTU Transmitter.
2. Faulty Water Temperature Switch.
3. Faulty Temperature Sensor
4. Unit in MANUAL Mode
5. Unit setpoint is greater than Over
Temperature Switch setpoint
1. Inspect and clean the BTU transmitter per Maintenance Section.
2. Test the temperature switch to insure it trips at its actual water
temperature setting.
3. Using the resistance charts in 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 20 degrees higher than
the unit’s setpoint.
HIGH WATER
TEMPERATURE
1. See HIGH WATER TEMP SWITCH
OPEN.
2. Temp HI Limit setting is too low.
1. See HIGH WATER TEMP 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.