AERCO KC Series Equipped with C-More version 3.04 - Manual (Page 72)

TROUBLESHOOTING
7-5
KC1000 WATER HEATER TROUBLESHOOTING TABLE – Continued
FAULT INDICATION PROBABLE
CAUSES
CORRECTIVE ACTION
HIGH GAS
PRESSURE
(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.