AERCO KC1000 Low NOx Water Heater July 2011 - Manual (Page 73)

TROUBLESHOOTING
7-9
KC1000 WATER HEATER TROUBLESHOOTING TABLE – Continued
FAULT INDICATION PROBABLE CAUSES CORRECTIVE ACTION
SSOV FAULT
DURING RUN
1. SSOV switch closed for 15
seconds during run.
1. Replace SSOV actuator.
SSOV RELAY
FAILURE
1. SSOV relay failed on
board.
2. Floating Neutral.
3. Hot and Neutral reversed
at SSOV
1. Ensure that Neutral and Earth Ground are
connected at the source and there is no voltage
measured between them. Measurement should
indicate near zero or no more than a few
millivolts.
2. Check the SSOV power wiring.
3. Press CLEAR button and restart unit. If fault
persists, replace Ignition/Stepper (IGST) Board.
SSOV
SWITCH OPEN
1. Actuator not allowing for
full closure of gas valve
2. SSOV powered when it
should not be
3. Defective Switch or
Actuator
4. Incorrectly wired switch.
1. Observe operation of the Safety Shut-Off Valve
(SSOV) through indicator on the Valve actuator
and ensure that the valve is fully and not partially
closing.
2. If the SSOV never closes, it may be powered
continuously. Close the gas supply and remove
power from the unit. Refer fault to qualified
service personnel.
3. Remove the electrical cover from the SSOV and
check switch continuity. If the switch does not
show continuity with the gas valve closed, either
adjust or replace the switch or actuator.
4. Ensure that the SSOV Proof of Closure switch is
correctly wired.
STEPPER MOTOR
FAILURE
1. Air/Fuel Valve out of
calibration.
2. Air/Fuel Valve unplugged.
3. Loose wiring connection to
the stepper motor.
4. Defective Air/Fuel Valve
stepper motor.
5. Defective Power Supply
Board or fuse.
6. Defective IGST Board
1. Refer to GF-112 and perform Stepper Test (para.
6.3.5) to ensure stepper motor rotates properly
between the 0% (fully closed) and 100% (fully
open) positions. Verify that the VALVE POSITION
bargraph and the dial on the Air/Fuel Valve track
each other to indicate proper operation. If
operation is not correct, perform the Stepper
Feedback Calibration (GF-112, para. 6.2.1).
2. Check to ensure that the Air/Fuel Valve is
connected to the Control Box.
3. .Inspect for loose connections between the
Air/Fuel Valve motor and the wiring harness.
4. Replace stepper motor.
5. Check DS1 & DS2 LEDs on Power Supply Board.
If they are not steady ON, replace Power Supply
Board.
6. Check “Heartbeat” LED DS1 and verify it is
blinking ON & OFF every second. If not, replace
IGST Board.