AERCO KC1000 Heater 2002 - Manual (Page 69)

TROUBLESHOOTING
7-7
KC1000 WATER HEATER TROUBLESHOOTING TABLE – Continued
FAULT INDICATION PROBABLE CAUSES CORRECTIVE ACTION
LINE VOLTAGE
OUT OF PHASE
1. Line and Neutral switched in AC
Power Box.
2. Incorrect power supply transformer
wiring.
1. Check hot and neutral in AC Power Box to ensure they are not
reversed
2. Check transformer wiring, in AC Power Box, against the power
box transformer wiring diagram to ensure it is wired correctly
LOW GAS
PRESSURE
1. Incorrect supply gas pressure.
2. Defective or incorrectly sized Gas
Supply Regulator.
3. Defective Low Pressure Gas Switch
1. Measure gas pressure upstream of the supply gas regulator with
the unit firing ensure it is 14” WC or greater.
2. Measure gas pressure downstream of the supply regulator with
unit firing and adjust the gas supply regulator to increase the
outlet gas pressure; if outlet gas pressure cannot be increased,
check the sizing of the Supply regulator.
3. Measure gas pressure at the low gas pressure switch, if it is
greater than 5” WC measure continuity across the switch and
replace if necessary.
LOW WATER
LEVEL
1. Insufficient water level in system
2. Defective water level circuitry.
3. Defective water level probe.
1. Check system for sufficient water level.
2. Test water level circuitry using the Control Box front panel LOW
WATER TEST and RESET buttons. Replace water level
circuitry if it does not respond.
3. Check continuity of probe end to the shell, change probe if there
is no continuity.
MODBUS COMM
FAULT
1. Water Heater not seeing information
from modbus network
1. Check network connections. If fault persists, contact qualified
Service Personnel.
PRG SWTCH CLOSED
DURING IGNITION
1. A/F Valve rotated open to purge and
did not rotate to ignition position
2. Defective or shorted switch.
1. Start the unit. The Air/Fuel Valve should rotate to the purge
(open) position, then back to ignition position (towards closed)
during the ignition cycle. If the valve does not rotate back to the
ignition position, check the Air/Fuel Valve calibration. If
calibration is okay, the problem may be in the Air/Fuel Valve or
the Control Box. Refer fault to qualified service personnel.
2. If the Air/Fuel Valve does rotate to the ignition position, check the
purge switch for continuity between the N.O. and COM terminals.
If the switch shows continuity when not in contact with the cam,
check to ensure that the switch is wired correctly (correct wire
numbers on the normally open terminals).