81
13
Troubleshooting
(continued)
Table 13-4 (continued from previous page) Troubleshooting Chart - Fault Messages Displayed on Boiler Interface
FAULT
DESCRIPTION
CORRECTIVE ACTION
FLUE TEMP
LIMIT
The stack temperature has exceeded the
Flue Temp Limit set parameters.
• Inspect the heat exchanger. Reference page 71 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 13-2D on page 76 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.
FLUE TEMP
HIGH
The stack temperature has exceeded the set
parameters for the boiler.
OUTLET MRHL
(will require a manual
reset once the condition
has been corrected.
Press the RESET button
on the
display to reset.)
The outlet water temperature has exceeded
the setting of the manual reset high limit.
• 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 6A - Hydronic Piping
for the proper piping methods for the Lochinvar Combi
Boiler.
• Check 120 vac to 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.
• 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 13-2A on page 76 of this manual. Replace
sensor if necessary.
• Check operation of diverter valve motor. Replace if
necessary.
OUTLET TEMP
HIGH
Outlet water temperature has exceeded the
maximum outlet water temperature.
OUTLET TEMP
DIFF
(will require a manual
reset once the condition
has been corrected.
Press the RESET button
on the display to reset.)
The temperature difference between the two
(2) outlet sensors is too high.
• Check wiring to sensor. Make sure wiring is
connected and not damaged. Reconnect / repair
wiring if necessary.
• Measure the resistance of the sensor and compare to
the resistance in Table 13-2C on page 76 of this manual.
Replace sensor if necessary.
• Replace control module.
FLUE SENSOR
FAULT
(will require a manual
reset once the condition
has been corrected.
Press the RESET button
on the display to reset.)
One or both of the flue sensors is open or
shorted.
• Inspect the flue sensor and associated wiring.
Measure the resistance of the flue sensor and
compare to Table 13-2D on page 76 of this manual.
Replace the sensor if necessary.
• Replace the main control board.
Installation & Service Manual
F I R E T U B E C O M B I
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