LP-387 Rev. 7.3.15
58
24 VOLT LOW LOU
PUMP ON
LOU indicates the 24 volt power supply on
the control is damaged or overloaded. This
code resets automatically if it is the result
of an overload and the overload condition
is removed. The second line indicates the
status of the pump. Note that while 24 volt
power is low, the pump output will be on.
1. Check line voltage. It must be between 100 and 128
volts.
2. If available, connect a PC and use HTP service software
to check the 24v supply display in the lower left corner of
the screen. The number displayed here must be greater
than 128 and should be no greater than 250. Use this as a
troubleshooting guide as you follow the steps below.
3. Remove the 10 pin Molex connector from the customer
connection board. If the message clears the problem is
with external sensor wiring. Examine the external sensor
wiring for shorts to the ground, repairing as necessary. If
the message is still present and the boiler is so equipped,
disconnect the UL 353 low water cut-o to see if the
message clears. Replace the faulty part. Check the low
voltage wire harness in boiler for shorts to ground.
4. If a message only occurs when the burner tries to light,
check the gas valve for excessive current draw.
5. If a message is present when the low voltage harness is
disconnected from the 926 control board, replace the 926
control board.
WATER HIGH TEMP F00
PUMP ON
F00 indicates the water in the boiler has
overheated. The boiler will not restart until it
cools suciently and a technician determines
and repairs the cause of overheating and
pushes RESET on the display. This is a serious
safety issue as indicated by the illuminated
red light and the word LOCKOUT ashing
on the display. During this lockout fault, the
pump will be on in an eort to cool the boiler
down.
1. Check circulator pump operation.
2. If the circulator pump is running, ensure there is water
in the system and that the water is moving through the
system as intended. Ensure that all correct ball valves and
or zone valves are open or closed as intended.
3. Observe the temperature/pressure gauge. If the water
is not too hot and this message is displayed, check the
wiring to the water ECO sensor and repair if necessary. If
the wiring is ok and this code is still present and the water
is not excessively hot, replace the ECO sensor.
FLUE TEMP/WAT LV F01
PUMP ON
F01 indicates that the ue temperature
limit switch of the boiler has tripped or that
the water level in the boiler is low (this will
only occur if the optional UL353 LWCO is
installed). This code indicates a serious safety
issue. The boiler will not restart until the ue
cools down suciently or the water level is
restored. A technician must repair the cause
of the problem and push the RESET button
rst on the low water cut-o control box,
then on the display. This situation is indicated
by the red light on the display and the word
LOCKOUT ashing on the display. During
this lockout fault, the pump will be on as
indicated on the second line of the display.
1. If the boiler has a UL353 LWCO, check if the red LED on
the LWCO control box is illuminated. If so, correct the low
water condition and press the reset button on the LWCO
control box to reset the LWCO. The LED should change
to green. Press the reset button on the front panel of the
boiler to reset the boiler control.
2. Check the ue for obstructions or any sign of damage,
especially signs of excessive heat. Repair as necessary.
Push the red reset button on the ue temperature switch
located on the ue inside the rear access door of the boiler.
NOTE: The switch temperature must be less than 90°F to
reset. Press the reset button on the display. Run the boiler
and check the ue temperature by using both an external
thermometer in the ue pipe and the ue temperature
display in the status screens. If the ue temperature is
within specs and the switch trips, replace the switch.
If the ue temperature is excessive, check and adjust
combustion controls on the boiler. If the problem persists,
inspect the target wall in the combustion chamber and
replace it if cracked or damaged.
SUPPLY SENSOR F02
PUMP ON
F02 indicates the supply temperature sensor
of the boiler has failed. The boiler will not
restart until a technician replaces the sensor
and pushes RESET on the display. This is
a serious safety issue as indicated by the
illuminated red light and the word LOCKOUT
ashing on the display. During this lockout
fault, the pump will be on.
1. Check the electrical connection to the thermistor on
the outlet manifold. Verify 5 VDC by checking the Molex
connector. If there is no 5 VDC, check the harness. If
harness is OK, replace the control. Verify thermistor
values by referencing chart in this manual.
2. Replace thermistor if necessary.
NOTE: The boiler will reset automatically once the fault
is corrected.
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