Watts AERCO Benchmark BMK750 Operation And Service Manual page 151

Benchmark with Edge [I]: Operation-Maintenance Manual
SECTION 9 – TROUBLESHOOTING
TABLE 9-1: Boiler Troubleshooting Procedures
Fault Probable Causes
Switch wired incorrectly.
3.
Defective Power Supply Board
4.
or fuse.
Defective IGST Board.
5.
Air/Fuel Valve not rotating to
1.
ignition position.
IGN
SWTCH
Defective Ignition switch.
2.
OPEN
DURING
IGNITION
Defective Power Supply Board
3.
or fuse.
Defective IGST Board.
4.
Interlock jumper not installed
1.
or removed.
Energy Management System
2.
does not have unit enabled.
INTERLOC
K OPEN
Device proving switch hooked
3.
to interlocks is not closed.
LINE Line and Neutral switched in
1.
VOLTAGE AC Power Box.
OMM-0145_A99 • GF-218 • Technical Support • (800) 526-0288 • Mon-Fri, 8 am - 5 pm EST
9/18/2019
Corrective Action
Check to ensure that the switch is wired
3.
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
4.
Board. If they are not steady ON, replace
Power Supply Board.
Check "Heartbeat" LED DS1 and verify it is
5.
blinking ON & OFF every second. If not,
replace IGST Board.
Start the unit. The Air/Fuel Valve should rotate
1.
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
Controller. Refer fault to qualified service
personnel.
If the Air/Fuel Valve does rotate to the ignition
2.
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
3.
Board. If they are not steady ON, replace
Power Supply Board.
Check "Heartbeat" LED DS1 and verify it is
4.
blinking ON & OFF every second. If not,
replace IGST Board.
Check for a jumper properly installed across
1.
the interlock terminals in the I/O box.
If there are two external wires on these
2.
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).
Check that proving switch for any device
3.
hooked to the interlock circuit is closing and
that the device is operational.
Check hot and neutral in AC Power Box to
1.
ensure they are not reversed.
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