Watts AERCO CFR 1500 Operation And Service Manual page 50

SECTION 9 TROUBLESHOOTING
TABLE 9-1: Boiler Troubleshooting Procedures
Fault Probable Causes
Faulty shell temperature sensor.
Unit in Manual mode.
Unit setpoint is greater than Over
Temperature switch setpoint.
System flow rate changes are
occurring faster than units can
respond.
See HIGH WATER TEMPERATURE
HIGH WATER
SWITCH OPEN.
TEMPERATURE
Temp HI Limit setting is too low.
Communication fault has occurred
between the PMC board and
IGN BOARD COMM
FAULT Ignition/Stepper (IGST) board.
32 Pin Ribbon cable defective.
Air/Fuel Valve not rotating.
Defective or shorted switch.
IGN SWITCH
CLOSED DURING
PURGE
Switch wired incorrectly.
Defective Power Supply Board or
fuse.
Defective IGST Board.
Air/Fuel Valve not rotating to
ignition position.
IGN SWTCH OPEN
Defective Ignition switch.
DURING IGNITION
Defective Power Supply Board or
fuse.
Defective IGST Board.
Interlock jumper not installed or
removed.
Energy Management System does
INTERLOCK OPEN
not have unit enabled.
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Corrective Action
Using the resistance charts in the manual to measure the
resistance of Shell sensor and BTU sensor at a known water
temperature.
If unit is in Manual mode, switch to Auto mode (Diagnostic >
Manual Mode).
Check setpoint of unit and setpoint of Temperature switch;
Ensure that the temperature switch is set higher than the unit's
setpoint.
If the system is a variable flow system, monitor system flow
changes to ensure that the rate of flow change is not faster
than what the units can respond to.
See HIGH WATER TEMPERATURE SWITCH OPEN.
Check Temp HI Limit setting.
Press CLEAR button and restart unit. If fault persists, contact
qualified Service Personnel.
Replace 32 Pin Ribbon cable.
Start the unit. The Air/Fuel Valve should rotate to the purge
(open) position. If the valve does not rotate at all or does not
rotate fully open, check the Air/Fuel Valve calibration. If
calibration is okay, the problem may be in the Air-Fuel Valve or
the Edge Controller. Refer to qualified service personnel.
If the Air/Fuel Valve does rotate to purge, check the ignition
switch for continuity between the N.O. and COM terminals. If
the switch shows continuity when not in contact with the cam
replace the switch.
Check to ensure that the switch is wired correctly (correct wire
numbers on the normally open terminals). If the switch is wired
correctly, replace the switch.
Check DS1 & DS2 LEDs on Power Supply Board. If they are not
steady ON, replace Power Supply Board.
Check "Heartbeat" LED DS1 and verify it is blinking ON & OFF
every second. If not, replace IGST Board.
Start unit. The Air/Fuel Valve should rotate to the purge (open)
position, then back to ignition (towards closed) during the
ignition cycle. If 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
Controller. Refer fault to qualified service personnel.
If the Air/Fuel Valve does rotate to the ignition position, check
the ignition position switch for continuity between the N.O.
and COM terminals when in contact with the cam.
Check DS1 & DS2 LEDs on Power Supply Board. If they are not
steady ON, replace Power Supply Board.
Check "Heartbeat" LED DS1 and verify it is blinking ON & OFF
every second. If not, replace IGST Board.
Check for a jumper properly installed across the interlock
terminals in the I/O box.
If there are two external wires on these terminals check any
Energy Management system to see if they have the units
disabled (a jumper may be temporarily installed to see if the
interlock circuit is functioning).
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