Troubleshooting
63
Faults are indicated by a flashing fault
code with fault code sysmbol “
U
” and
the reset button
is illuminated.
For fault code explanations see the
following table.
Diagnostics table: Faults with fault display on control unit
Fault mes-
sage in dis-
play window
System behavior
Cause
Corrective measures
0b
Burner blocked
Insufficient water flow.
Incorrect flow direction.
Defective flow switch.
Check proper heating circuit pump
size and operation.
Check flow direction.
Check flow switch connection cable.
0c
Burner blocked
Insufficient power supply
Contact your local hydro company.
30
Burner blocked
Boiler temperature sensor shorted
out
Check the boiler temperature sensor
(see page 65).
38
Burner blocked
Boiler temperature sensor lead break
Check the boiler temperature sensor
(see page 65).
b1
Control mode
Communication fault - internal pro-
gramming unit
Check connections and replace the
control unit if necessary.
b5
Control mode
Internal fault
Replace control unit.
e4
Burner blocked
Fault with the supply voltage (power
pump module)
Check connections. Replace control
unit.
e5
Burner blocked
Internal fault
Check ignition and ionization elec-
trodes and leads.
Press “Reset”.
e6
Burner blocked
Water pressure too low
Top up water .
f0
Burner blocked
Internal fault
Replace control unit.
f2
Burner in fault mode
Fixed high limit tripped
Check the heating system water
level. Check the circulation pump
operation. Vent the heating system
of air. Check the fixed high limit and
leads.
Press “Reset”.
f3
Burner in fault mode
The flame signal is already present at
burner start
Check the ionization electrode and
leads.
Press “Reset”.
f4
Burner in fault mode
No flame signal is present
Check the ionization electrode and
leads, check the gas pressure, check
the gas combination valve, control
unit and condensate drain see page
56).
Press “Reset”.
f5
Burner blocked
Faulty air pressure switch
Check the air pressure switch and
the interconnecting cable.
Check the burner air/gas
mixture damper. Reference the
Burner Damper Replacement
Instructions.
Diagnosis
(continued)
5
5
8
1
7
7
5
1
.3
5
5
8
1
7
7
5
1
.3
tr
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