Lochinvar KNIGHT 81-286 Service Manual page 44

3
Troubleshooting
Table 3-4 (continued from previous page) Troubleshooting Chart - Fault Messages Displayed on Boiler Interface
FAULT
Flue Temp High
Delta T High
Outlet Temp
High
44
DESCRIPTION
The stack temperature has exceeded the set
parameters for the boiler.
The temperature rise across the heat
exchanger has exceeded the set parameters
for the boiler.
Outlet water temperature has exceeded the
maximum outlet water temperature.
CORRECTIVE ACTION
• 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 the main control board.
• 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 Boiler Installation and Operation Manual
for the proper piping methods for the Knight 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.
Section 6 - Hydronic Piping of the Knight
Boiler Installation and Operation Manual for boiler
pump specifications.
• 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 Boiler Installation and Operation Manual
for the proper piping methods for the Knight boiler.
• Check for 120 vac to the boiler pump motor on a call
for heat. If voltage is not present, check 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.
Service Manual
Reference