Lochinvar KNIGHT 399 - Manual (Page 38)

3
Troubleshooting
38
Service Manual
Table 3F (continued from previous page) Troubleshooting Chart - Fault Messages Displayed on Boiler Interface
FAULT DESCRIPTION CORRECTIVE ACTION
Temp O/Shoot
(continued)
Outlet water temperature has exceeded the
maximum outlet water temperature. • 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.
• Replace the main control board.
Rem Ctrl Flt
External control is cycling too often. • Check set point of the external control.
• Check the wiring between the external control and the
unit.
• Replace the control.
Parameters
Progr
(will require a manual
reset once the condition
has been corrected. Press
the RESET button on the
SMART SYSTEM display
to reset.)
After downloading parameters from a laptop,
the main control board must be reset.
• Press the ENTER/RESET button on the SMART
SYSTEM display panel.
APS
Open
(will require a manual
reset once the condition
has been corrected. Press
the RESET button on the
SMART SYSTEM display
to reset.)
Air pressure switch contacts are open.
• Check the wiring connections to switch. Wires should
be connected to the common and normally closed
terminals.
• Vent/air intake lengths exceed the maximum allowed
lengths. Refer to Section 3 - General Venting of the
Knight XL Installation and Operation Manual for
proper lengths.
• Check for obstruction or blockage in the vent/air
intake pipes or at terminations.
• Check reference hoses connected to the air pressure
switch for blockage or obstruction.
• Inspect the burner. Reference page 26 of this manual
for removal and cleaning procedures. Replace if
necessary.
• Inspect the heat exchanger. Reference page 27 of this
manual for removal and cleaning procedures.
Replace if necessary.
• Faulty air pressure switch. Replace switch.