Knight WH 399, Руководство по обслуживанию

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3
Troubleshooting
(continued)
39
Service Manual
Table 3-4 (continued from previous page) Troubleshooting Chart - Fault Messages Displayed on Boiler Interface
FAULT DESCRIPTION CORRECTIVE ACTION
Flame Fail
Running
(will require a manual
reset once the condition
has been corrected.
Press the RESET
button on the SMART
SYSTEM display to
reset.)
The unit was running and lost the flame signal.
This condition occurred five (5) straight times
during the same call for heat.
• Check wiring harness connection at the gas valve and
at the main control board.
• Inspect spark electrode and associated wiring for
damage and connection. Reference page 31 of this
manual for removal and cleaning procedures.
Replace if necessary.
• Check for proper electrical grounding of the unit.
• Check incoming supply gas pressure. Natural gas
pressures should be between 4 - 14 inches w.c. and
LP gas pressures should be between 8 - 14 inches w.c.
Refer to Section 7 - Gas Connections of the Knight
Wall Mount Boiler Installation and Operation Manual
for detailed information concerning the gas supply.
• Verify that the plastic hose from the gas valve to the air
inlet is connected and is not damaged.
• Verify that the vent/air intake pipes are correctly
installed and that there are no obstructions.
• Check for 24 vac to the gas valve at the 2-pin
connection on the side of the main control board during
the ignition attempt. If no voltage is present, replace
the main control board.
• If 24 vac is present at the main control board, check
the wiring between the main control board and the gas
valve. Replace the wiring if necessary.
• If 24 vac is present, check the outlet of the valve to
ensure the valve is flowing gas. With a manometer
connected to the outlet tap of the gas valve, when the
unit is in the prepurge period, there should be a
negative pressure present. When the valve is
energized a change in pressure should occur. If the
pressure change does not occur, the gas valve is not
opening. Replace the gas valve.
• Inspect and clean the heat exchanger as necessary.
Reference page 32 of this manual for cleaning
procedures.
Flame
Sequence
(will require a manual
reset once the condition
has been corrected.
Press the RESET
button on the SMART
SYSTEM display to
reset.)
The flame detector circuit is seeing a flame
signal while no flame is present.
• Check supply voltage for proper polarity.
• Check external wiring for voltage feedback.
• Check the flame rod and make sure it is clean.
• Check the internal wiring for bad connections.
• Replace main control board.