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3 Troubleshooting (continued)
Table 3G (continued from previous page) Troubleshooting Chart - Fault Messages Displayed on Boiler Interface
FAULT DESCRIPTION CORRECTIVE ACTION
Blower Proving
Switch Open 2
(will require a manual
reset once the condition
has been corrected. Press
the RESET button on the
display to reset.)
Pressure switch contacts are open.
• Check the wiring connections to switch. Wires should
be connected to the common and normally open
terminals.
• Remove switch and check for blockage in the orifice.
• Vent/air intake lengths exceed the maximum allowed
lengths. Refer to Section 2 - General Venting of the
Crest Installation and Operation Manual for
proper lengths.
• Check for obstruction or blockage in the vent/air
intake pipes or at terminations.
• Inspect the burner. Reference page 34 of this manual
for removal and cleaning procedures. Replace if
necessary.
• Verify combustion air blower 2 is operating. Replace if
necessary.
• Inspect the heat exchanger. Reference page 35 of
this manual for removal and cleaning procedures.
• Faulty pressure switch. Replace switch.
Burner Supply
Temperature
Differential
(will require a manual
reset once the condition
has been corrected. Press
the RESET button on the
display to reset.)
Combustion air to burner 1 temperature
is higher than combustion air to burner 2
temperature or vice versa.
• Inspect the combustion air temperature sensor and
associated wiring.
• Measure the resistance of the combustion air
temperature sensor and compare to Table 3E on
page 38 of this manual
• Replace the sensor if necessary.
• Verify that the vent / air intake pipes are properly
installed and that there are no obstructions.
Burner Supply
Temperature
High 1
(will require a manual
reset once the condition
has been corrected. Press
the RESET button on the
display to reset.)
Combustion air temperature is very high.
• Check if the vent backflow preventer is installed for
boilers commonly vented.
• Check if the vent backflow preventer is stuck open
while the unit is off.
• Inspect the combustion air temperature sensor and
associated wiring.
• Measure the resistance of the combustion air
temperature sensor and compare to Table 3E on
page 38 of this manual.
• Replace the sensor if necessary.
Burner Supply
Temperature
High 2
(will require a manual
reset once the condition
has been corrected. Press
the RESET button on the
display to reset.)
Combustion air temperature is very high.
• Check if the vent backflow preventer is installed for
boilers commonly vented.
• Check if the vent backflow preventer is stuck open
while the unit is off.
• Inspect the combustion air temperature sensor and
associated wiring.
• Measure the resistance of the combustion air
temperature sensor and compare to Table 3E on
page 38 of this manual.
• Replace the sensor if necessary.
Service Manual
49