Aerco GF-110 Benchmark Series Installation, Operation & Maintenance Instructions Manual page 65

TROUBLESHOOTING
FAULT INDICATION
LINE VOLTAGE 1. Line and Neutral switched in AC
OUT OF PHASE
2. Incorrect power supply transformer
LOW GAS 1. Incorrect supply gas pressure.
PRESSURE
2. Defective or incorrectly sized Gas
3. Defective Low Pressure Gas Switch
LOW WATER 1. Insufficient water level in system
LEVEL
2. Defective water level circuitry.
3. Defective water level probe.
MODBUS COMM 1. Boiler not seeing information from
FAULT
PRG SWTCH CLOSED 1. A/F Valve rotated open to purge and
DURING IGNITION
2. Defective or shorted switch.
3. Switch wired incorrectly.
4. Defective Power Supply Board or
8-7
TABLE 8-1. BOILER TROUBLESHOOTING – Continued
PROBABLE CAUSES
Power Box.
wiring.
Supply Regulator.
Modbus network
did not rotate to ignition position
fuse
CORRECTIVE ACTION
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
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.
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.
1. Check network connections. If fault persists, contact qualified
Service Personnel.
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).
3. If the switch is wired correctly, replace the switch.
4. Check DS1 & DS2 LEDs on Power Supply Board. If they are not
steady ON, replace Power Supply Board.