0020209589_04 ecoTEC pro Installation and maintenance instructions
45
Message
Possible cause
Measure
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, CO
₂
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.49
Fault: eBUS
Undervoltage on the eBUS
▶
Check: eBUS (overload, two power supplies with different po-
larities, short circuit).
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.
F.68
Fault: Flame signal un-
stable
Flame monitor reports an un-
stable flame signal
▶
Check: Air ratio, gas flow pressure, condensate route (block-
age), gas injector, ionisation flow (cable, electrode), flue gas
recirculation.
F.70
Fault: Invalid Device Spe-
cific Number
Incorrect/missing Device
Specific Number or
incorrect/missing coding resistor
▶
If the display and PCB have been replaced, change the Device
Specific Number under
D.93
.
F.71
Fault: Flow sensor
Flow temperature sensor re-
turns implausible values
▶
Check: Flow temperature sensor (correct thermal connection).
F.72
Fault: Flow/return sensor
Temperature difference
between flow and return
temperature sensor is too great
▶
Check: Flow temperature sensor/return temperature sensor
(function, correct thermal connection).
F.73
Fault: Water press. sensor
(signal too weak)
Water pressure sensor reports
that the water pressure is too
low
▶
Check: Water pressure, earth connection, cable, plug, water
pressure sensor (short circuit to GDN).
F.74
Fault: Water press. sensor
(signal too strong)
Water pressure too high
1.
Drain water.
2.
Check the water pressure sensor.
F.75
Fault: Pump/ water short-
age
Insufficient pressure jump de-
tected when starting the pump
1.
Check: Water pressure sensor, heating pump (blockage),
heating circuit (air, sufficient water volume), adjustable by-
pass, external expansion vessel (must be connected at the
return). Activate check programme P.0.
2.
If a low loss header or heating pipes with a diameter greater
than 1 1/2 inch are installed, replace the 3/4-inch seal in the
heating flow with a screen. If required, install the F.75 service
set.
F.77
Fault: Flue non-ret.
valve/condens. pump
No flue non-return flap feed-
back; condensate pump over-
flow
▶
Check: Cable to VR40 accessory, flue non-return flap (wiring,
feedback switch), condensate pump, bridge from the surface-
mounted thermostat, 2 in 7 multi-functional module (bridge).
F.78
Interrupt.: DHW outlet
sensor on ext. contr.
UK link box is connected
without the domestic hot water
temperature sensor being
bridged
1.
Check: Accessory (configuration/electrical connection).
2.
The unit displays a fault, but the unit has not malfunctioned.
