Instructions / Assembly
74
Fault Code TT
Temperature Blocking TT Demand
TEMPER BLOCKING
PUMP ON TT
This screen indicates a temporary hold on the burner. There is a demand on the boiler, the pump is powered on, but the
temperature of the water at the supply sensor is too high for the boiler to ignite. This occurs because the water tempera-
ture measured by the supply sensor is higher than the boiler temperature – ignition diff setting. This error will clear itself
when the water temperature measured by the supply sensor is less than the boiler temperature – ignition diff setting.
Fault Code DHW
Temperature Blocking DHW Demand
TEMPER BLOCKING
PUMP ON DHW
This display indicates a temporary hold on the burner. There is a demand on the boiler from the DHW circuit for heat,
the pump is powered on, but the boiler supply sensor indicates that the water temperature is too high to ignite. This is a
temporary hold on the burner only and all other functions will remain functioning properly. This error will clear itself when
either the boiler supply temperature drops below the BOILER SUPPLY minus boiler supply differential (5
o
F) or DHW
SETPOINT is satisfied and no longer calls for heat.
Fault Code PRO
LOW WATER PRESS
PUMP OFF PRO
This display indicates that there is low water pressure in the
boiler. This code will reset automatically after the water
pressure is high enough for the boiler to run safely. The
second line indicates the status of the pump. Note that while
the water pressure is low, the pump will be off.
1. Assure that the system pressure is above 10 psig.
2. Check for leaks in the system piping.
Fault Code FLU
HIGH FLUE PRESS FLU
PUMP ON
This display indicates that there is excessive flue
pressure. This code resets automatically after
the high pressure condition is resolved. The sec-
ond line indicates the status of the pump.
1. Assure that the flue is not blocked.
2. Check the switch wiring by applying a jumper in place of the
switch. If the code clears with the jumper in place, REPLACE the
flue switch and connect the wires to the new switch BEFORE
running boiler.
WARNING: Do not use jumper to remedy an FLU error. Faulty switch MUST be replaced. Failure to do so could result in serious injury or death.
Fault Code LOU
24 VOLT LOW LOU
PUMP ON
This display indicates that
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
that 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 PC, and using HTP service software 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 customer connection board. If the message
clears, then the problem is with the 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-off 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 exces-
sive current draw.
5. If a message is present with the low voltage harness disconnected from the 926
control board, replace the 926 control board.
Fault Code F00
WATER HIGH TEMP F00
PUMP ON
This display indicates if the water in the boiler
has overheated. This code indicates a serious
safety issue and the boiler will not restart until it
cools sufficiently and a technician repairs the
cause of overheating and pushes the RESET
button on the display. This is a serious situation
and is indicated by the red light on the display
illuminating and the word LOCKOUT flashing on
the display. During this lockout fault, the pump
will be on as indicated on the second line in an
effort to cool the boiler down.
1. Check circulator pump operation
2. If the circulator pump is running, be sure that there is water in
the system and that the water is moving through the system as
intended. Be sure 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.
SCREEN
DESCRIPTION
POSSIBLE REMEDY
Fault Code F01
FLUE TEMP/WAT LV F01
PUMP ON
This display indicates that the flue 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 flue cools down
sufficiently or the water level is restored. A tech-
nician must repair the cause of the problem and
push the RESET button first on the low water
cut-off control box, then on the display. This
situation is indicated by the red light on the
display and the word LOCKOUT flashing 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 con-
dition 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 flue for obstructions or any sign of damage, especially
signs of excessive heat. Repair as necessary. Push the red reset
button on the flue temperature switch located on the flue 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 flue temperature by using both an
external thermometer in the flue pipe and the flue temperature
display in the status screens. If the flue temperature is within specs
and the switch trips, replace the switch. If the flue 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.