Service Manual

3 Troubleshooting (continued)
Service Manual
39
Table 3F (continued from previous page) Troubleshooting Chart - Fault Messages Displayed on Boiler Interface
FAULT DESCRIPTION CORRECTIVE ACTION
Service Blk
While the unit is in Service Mode, the outlet
temperature has exceeded 185°F.
• Establish a heating load to remove the heat from the
boiler loop.
• 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 XL Installation and Operation Manual for the
proper piping methods for the Knight XL boiler.
• Check voltage to the boiler pump motor on a call for
heat. If voltage is not present, check the wiring back
to the pump relay. Replace the pump relay 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 boiler pump is the proper size. Reference
Section 6 - Hydronic Piping of the Knight
XL Installation and Operation Manual for boiler
pump specifications.
Low 24 VAC
120 VAC input to the main control board has
dropped below 80 VAC.
• Check 120 VAC supply to the transformer.
• Check wiring connections at the low voltage terminal
strip.
• Check the wire size/length to remote devices.
• Replace the transformer.
Watch Dog Error
The main control board has detected an
internal fault.
• Replace the main control board.
Write EEProm
The main control board has detected an
internal fault.
• Replace the main control board.
CRC Parameters
The main control board has detected an
internal fault.
• Replace the main control board.
No Error Stored
The main control board has detected an
internal fault.
• Press the ENTER/RESET button on the SMART
SYSTEM display panel.