AERCO KC1000 Heater Mar 2011 - Manual (Page 69)

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.