0020244997_07 Installation and maintenance instructions 61
Code/meaning Possible cause Measure
F.22 Safety switch-off: Low wa-
ter pressure
No/insufficient water in the
product or the water pressure is
too low
1. Check: Plug, cable to heating pump or water pressure
sensor, water pressure sensor, heating pump.
2. Activate and purge check programme P.0.
F.23 Safety switch-off:
Temp.spread too large
Temperature spread too great.
Water circulation too low
▶ Check: Plug, cable to heating pump/water pressure sensor,
air/insufficient water in the heating circuit, flow and return tem-
perature sensor inverted, strainer in the hydraulic block, water
pressure sensor, heating pump (sufficient circulation, stage 2:
D.19, D.14, non-return valve). Activate check programme P.0.
F.24 Safety switch-off: Temp.
incr. too fast
Temperature increase too fast ▶ Check: Plug, cable to the heating pump, air/insufficient water
in the heating circuit, internal air vent (function), heating pump
(system pressure too low, temperature gradient too great on
heating flow, non-return valve). Activate check programme P.0.
F.25 Safety switch-off: Flue
temp. too high
flue gas temperature too high ▶ Check: Plug, safety cut-out plug, cable harness, cable to the
heating pump, internal air vent (function), flue gas route (block-
age, adverse wind conditions, flue pipework too long), insuf-
ficient water in heating circuit, heating pump, activate check
programme P.0.
F.26 Fault: Fuel valve not work-
ing
Gas valve assembly stepper
motor defective or not connec-
ted
▶ Check: Gas valve assembly stepper motor (plug, cable, pas-
sage for rinsing, voltage), multiple plug, cable harness.
F.27 Safety switch-off: Flame
simulation
Monitoring electrode reports an
incorrect flame
▶ Check: Gas pressure at upper test opening, monitoring elec-
trode, PCB, gas solenoid valve.
F.28 Start-up failure: Ignit. un-
successful
Failure during start-up or igni-
tion unsuccessful. Gas pressure
monitor or thermal cut-out has
been triggered.
▶ Check: Gas stopcock, gas flow pressure, gas valve assembly,
air intake pipe (blockage, loosened screw), condensate route
(blockage), multiple plug, cable harness, ignition transformer,
ignition cable, ignition plug, ignition electrode, monitoring elec-
trode, electronics, earthing, CO₂ setting.
F.29 Operating failure: Ignit.
unsuccessful
Gas supply interrupted intermit-
tently. Re-ignition failed.
▶ Check: Flue gas recirculation, condensate route (blockage),
earthing, cable to the gas valve assembly and electrode (loose
connection).
F.32 Fault: Fan Fan defective or not connected ▶ Check: Plug, cable harness, fan (blockage, function, correct
speed), Hall sensor, PCB, flue gas route (blockage).
F.42 Fault: Coding resistor Coding resistor or gas group
resistor causes a short circuit
▶ Check: Plug, earth connection, cable, output coding resistor (in
the cable harness).
F.49 Fault: eBUS Undervoltage on the eBUS ▶ Check: eBUS (overload, two power supplies with different po-
larities, short circuit).
F.52 Mass flow sensor not con-
nected
Mass flow sensor defective or
not connected
▶ Check: Plug, cable harness, mass flow sensor.
F.53 Gas valve assembly mass
flow unexpected
The mass flow through the gas
valve assembly is not as expec-
ted.
▶ Check: Gas flow pressure too low, sharp drop in pressure
during ignition or full load, filter below Venturi filter cap wet
or blocked, internal pressure measuring point in the Venturi
blocked (do not use any lubricants on the O-ring in the Ven-
turi), gas valve assembly does not regulate correctly.
F.54 Fault: Boiler start No gas inlet pressure or insuffi-
cient gas inlet pressure causes
faults when the product is star-
ted
▶ Check (in conjunction with F.28/F.29): Gas stopcock, gas valve
assembly, plug, cable harness.
F.55 Fault: CO sensor All-gas sensor defective or has
short-circuited
▶ Check: Plug, cable harness, all-gas sensor, PCB.
F.56 Safety switch-off: CO limit
exceeded
Safety shutdown after the CO
limit value is exceeded
▶ Check: Gas valve assembly, plug, cable harness. If the fault
occurs again after being cleared, the gas valve assembly is
defective.
F.57 Fault: Measuring program Regulation fault caused by cor-
roded ignition electrode
▶ Check: Ignition electrode, PCB (microcontrol).
F.61 Fault: Fuel valve actuation The gas valve assembly cannot
be actuated
▶ Check: Cable harness, plug, gas valve assembly (rinse), PCB.
F.62 Fault: Fuel valve switch-off
delay
Delayed switch-off sequence for
the gas valve after the flame is
extinguished
▶ Check: Gas valve, surface of the burner (dirt), plug, cable har-
ness, PCB.
F.63 Fault: EEPROM EEPROM faulty ▶ Replace: PCB.
F.64 Fault: Electronics/sensor Electronics, safety-relevant
sensor or cable defective
▶ Check: Flow sensor, cable to the sensor, flame recording
sensor (e.g. ionisation electrode) for an unstable signal,
electronics.
F.65 Fault: Electronics temp. Electronics defective or too hot
due to external influences
1. Check: PCB.
2. If required, reduce the environmental temperature.
F.67 Fault: Electronics/flame Implausible flame signal ▶ Check: Cable harness, flame monitor, PCB.
To Next Page
Loading...
Need help?
General