Lochinvar FTxl 500 Service Manual page 44

3
Troubleshooting
Table 3-4 (continued from previous page) Troubleshooting Chart - Fault Messages Displayed on Boiler Interface
FAULT
Outlet MRHL
(cont'd)
(will require a manual
reset once the condition
has been corrected. Press
the RESET button on the
SMART SYSTEM display
to reset.)
Fan Speed
(will require a manual
reset once the condition
has been corrected. Press
the RESET button on the
SMART SYSTEM display
to reset.)
Inlet, Outlet, or
Flue Sensor Fault
(will require a manual
reset once the condition
has been corrected. Press
the RESET button on the
SMART SYSTEM display
to reset.)
44
DESCRIPTION
The outlet water temperature has exceeded
the setting of the manual reset high limit.
The actual fan RPM is 30% lower or higher
than the fan speed target.
Blown fuse.
Either the flue, inlet water, or outlet water
temperature sensor has been disconnected
or shorted.
Service Manual
CORRECTIVE ACTION
• If 120 vac is present on a call for heat and the boiler
pump is not operating, replace the pump.
• If the system pump is a variable speed pump, ensure
that the system flow is not less than the boiler flow.
• If operating on something other than an outlet sensor,
check temperature setting of the main control board.
• Check resistance of water sensors and compare to
Table 3-2A on page 39 of this manual.
sensor if necessary.
• Replace the main control board if necessary.
• Vent/air intake lengths exceed the maximum allowed
lengths. Refer to Section 3 - General Venting of the
FTXL Installation and
proper lengths.
• Check for obstruction or blockage in the vent/air
intake pipes or at terminations.
• Check the wiring connections at the fan and at the
main control board.
• Check the fan using the RLY20119 fan test tool.
• Replace the fan.
• Replace the main control board.
• Replace fuse F2 on the control board, see page 37
of this manual.
• Check the sensors and their associated wiring.
Repair or replace the sensor or wiring if damaged.
• Measure the resistance of the sensors and compare
the resistance to the tables on page 39 of this
manual.
• Replace the sensor if necessary.
Replace
Operation Manual for