Vaillant ecoTEC plus VU 6/5-5 Series Installation And Maintenance Instructions Manual page 62

Code/meaning
F.68 Fault: Flame signal un-
stable
F.70 Fault: Invalid Device Spe-
cific Number
F.71 Fault: Flow temperature
sensor
F.72 Fault: Flow/return temper-
ature sensor
F.73 Fault: Water press. sensor
(signal too weak)
F.74 Fault: Water press. sensor
(signal too strong)
F.75 Fault: Pump/ water short-
age
F.77 Fault: Flue non-ret.
valve/condens. pump
F.78 Interruption: DHW outlet
sensor at ext. control
F.80 Fault: actoSTOR inlet
sensor
F.81 Fault: cylinder charging
pump
F.82 Fault: Ext. current anode
F.83 Fault: NTC temp. gradient
F.84 Fault: NTC temp. diff. im-
plausible
F.85 Fault: NTCs fitted incor-
rectly
F.90 Fault: Communication
F.91 Fault: actoSTOR sensor
F.92 Fault: Incorrect gas type
F.93 Fault: Check gas route
F.94 Fault: Vortex and differen-
tial pressure
62
Possible cause
Flame monitor reports an un-
stable flame signal
Incorrect/missing Device
Specific Number or
incorrect/missing coding resistor
Flow temperature sensor re-
turns implausible values
Temperature difference
between flow and return
temperature sensor is too great
Water pressure sensor reports
that the water pressure is too
low
Water pressure too high
Insufficient pressure jump de-
tected when starting the pump
No flue non-return flap feed-
back; condensate pump over-
flow
UK link box is connected
without the domestic hot water
temperature sensor being
bridged
Inlet temperature sensor defect-
ive or not connected
Cylinder is not fully charged
after specified time
External current anode defect-
ive or not connected
Temperature difference
between flow and return
temperature sensor is too small
Temperature difference is im-
plausible
Flow/return temperat-
ure sensors returning
incorrect/implausible values
Communication with actoSTOR
interrupted
Sensor on the actoSTOR is
defective
The coding resistor on the PCB
does not match the gas group
that is entered
Combustion quality outside the
permitted range
Sensors return implausible val-
ues.
Measure
▶
Check: Air ratio, gas flow pressure, condensate route (block-
age), gas injector, ionisation flow (cable, electrode), flue gas
recirculation.
▶
If the display and PCB have been replaced, change the Device
Specific Number under D.93.
▶
Check: Flow temperature sensor (correct thermal connection).
▶
Check: Flow temperature sensor/return temperature sensor
(function, correct thermal connection).
▶
Check: Water pressure, earth connection, cable, plug, water
pressure sensor (short circuit to GDN).
1. Drain water.
2. Check the water pressure sensor.
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.
▶
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).
1. Check: Accessory (configuration/electrical connection).
2. The unit displays a fault, but the unit has not malfunctioned.
▶
Check (only in conjunction with F.91): NTC sensor, plug, cable
harness, PCB.
▶
Check (only in conjunction with F.91): Cylinder charging
sensor, cylinder sensor, impeller sensor/limiter, prioritising
diverter valve, pump, actoSTOR pump (air), cable harness,
secondary heat exchanger (blockage).
▶
Check: Cable harness, external current anode. If the external
current anode is not installed: Plug edge connector X43 with a
bridge into the PCB.
▶
Check: Flow/return temperature sensor (function, correct
thermal connection), sufficient water volume.
▶
Check: Flow/return temperature sensor (correct thermal con-
nection, sensors are inverted).
▶
Check: Flow/return temperature sensor (correct thermal con-
nection).
1. Check: Plug, check cable harness to the actoSTOR module
(PEBus).
2. If the product is to be operated without an actoSTOR:
Set D.092=0, if required, plug edge connector X31 into
the BMU, if required plug edge connector X1 into the
actoSTOR.
▶
Check: Plug, cable harness, sensor.
1. Check: Coding resistor.
2. Carry out the gas family check again and enter the correct
gas group.
▶
Check: Gas injector (suitable for the gas group), flue gas re-
circulation, gas group, internal pressure measuring point in the
Venturi (blockage). Do not use any lubricants on the O-ring in
the Venturi.
▶
Check: Cable harness, plug, sensors.
Installation and maintenance instructions 0020244997_07