AERCO KC Series Equipped with C-More Controller for Massachusetts Only - Manual (Page 68)

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.