3
Troubleshooting
(continued)
43
Service Manual
Table 3-4 (continued from previous page) Troubleshooting Chart - Fault Messages Displayed on Boiler Interface
FAULT
DESCRIPTION
CORRECTIVE ACTION
Flue Temp High
The stack temperature has exceeded the
set parameters for the boiler.
• Inspect the heat exchanger. Reference page 32
of this manual for the procedure on how to clean
the flue side of the heat exchanger.
• Inspect the flue sensor and associated wiring.
Measure the resistance of the flue sensor and
compare to Table 3-2D on page 35 of this manual.
Replace the sensor if necessary.
• Verify that the vent/air intake pipes are properly
installed and that there are no obstructions.
• Replace main control board.
Flue Temp Limit
(will require a manual
reset once the condition
has been corrected. Press
the RESET button on the
SMART SYSTEM
display
to reset.)
The stack temperature has exceeded the
Flue Temp Limit set parameters.
• Inspect the heat exchanger. Reference page 32
of this manual for the procedure on how to clean
the flue side of the heat exchanger.
• Inspect the flue sensor and associated wiring.
Measure the resistance of the flue sensor and
compare to Table 3-2D on page 35 of this manual.
Replace the sensor if necessary.
• Verify that the vent/air intake pipes are properly
installed and that there are no obstructions.
• Replace main control board.
Delta T High
The temperature rise across the
heat exchanger has exceeded the set
parameters for the boiler.
• Verify that the system is full of water and that all air
has been properly purged from the system.
• Verify that the boiler is piped properly into the heating
system. Refer to Section 6 - Hydronic Piping of the
Knight Wall Mount Installation and Operation Manual
for the proper piping methods for the Knight wall
mount
boiler.
• Check for 120 vac to the boiler pump motor on a call
for heat. If voltage is not present, check the wiring
back to the main control board. Replace the main
control board if necessary.
• If 120 vac is present on a call for heat and the boiler
pump is not operating, replace the pump.
• Verify that the boiler pump is set to the proper speed
or that the pump is the proper size. Reference
Section 6 - Hydronic Piping of the Knight Wall Mount
Boiler Installation and Operation Manual for boiler
pump
specifications.
Summary of Contents for WH 399
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