Vaillant ecoTEC plus VU Series Installation And Maintenance Instructions Manual page 62

Code/meaning
F.326
The hydraulic sensor and actu-
ator test has detected at least
two hydraulic components that
are not working.
F.327
The minimum heating volume
flow is limited due to there be-
ing no domestic hot water cir-
cuit connected.
F.330
The pump is not responding to
commands during the hydraulic
test.
F.334
The configuration of the flue
system was not completed.
F.336
The unit is not permitted in this
configuration.
F.337
The multiple-flue configuration
conversion set is not suitable
for the heat cell.
F.338
Incorrect multiple-flue configura-
tion setting
F.342
The air-mass flow is not within
the permitted limits.
F.343
The signal for the air-mass flow
sensor is not plausible.
F.344
The control electrode can no
longer be used.
62
Possible cause
3-port diverter valve defective or
blocked
Plug on 3-port motorised valve
loose/not plugged in
Interruption in the wiring har-
ness
Domestic hot water circuit not
connected
External pump runs continu-
ously
The pump is defective.
Cylinder bypass not connected
Domestic hot water circuit
clogged/blocked
Fault in the electrical connection
for the pump
The pump is defective.
Flue system configuration not
completed
Flue system configuration set
incorrectly
Incorrect gas type set
The multiple-flue configuration
conversion set is not suitable
for the heat cell
Multiple-flue configuration set
incorrectly
Fan speed does not correspond
to the target value
Plug on PCB loose/not plugged
in
Interruption in the wiring har-
ness
Plug for air-mass flow sensor
loose/not plugged in
You exit the measuring range
permanently. Air-mass flow
sensor defective
Flue gas pipe blocked
Plug for air-mass flow sensor
loose/not plugged in
Plug on PCB loose/not plugged
in
Interruption in the wiring har-
ness
Measurement discrepancy too
high. Air-mass flow sensor dirty.
You exit the measuring range
permanently. Air-mass flow
sensor defective
PCB defective
Transmission fault for calibra-
tion values
Measure
▶
Check and, if required, replace the 3-port diverter valve.
▶
Check the plug and the plug connection on the 3-port motor-
ised valve.
▶
Check the wiring harness including all plug connections and, if
required, replace it.
▶
Connect the domestic hot water circuit.
▶
Check the external pump and the system configuration.
▶
Check and, if required, replace the pump.
▶
Check the cylinder connection pipes.
▶
Check the secondary heat exchanger for dirt.
▶
Check the wiring harness between the PCB and pump, includ-
ing all plug connections.
▶
Check and, if required, replace the pump.
▶
Check the flue gas configuration and complete this.
▶
Set the approved flue system configuration.
▶
Check the gas type and the gas type setting under D.156 and
D.157.
▶
Check and, if required, replace the conversion set comprising
air intake pipe with integrated non-return valve and air-mass
flow sensor.
▶
Set the approved flue system configuration.
▶
Use D.033 and D.034 to check whether the fan speed deviates
by more than 20–30 rpm.
▶
Check the plug and the plug connection.
▶
Check the wiring harness including all plug connections and, if
required, replace it.
▶
Check the plug and the plug connection for the air-mass flow
sensor.
▶
Replace the entire air intake pipe.
▶
Check the entire flue gas pipe.
▶
Check the plug and the plug connection for the air-mass flow
sensor.
▶
Check the plug and the plug connection.
▶
Check the wiring harness including all plug connections and, if
required, replace it.
▶
Check the air-mass flow sensor for dirt.
▶
Replace the entire air intake pipe.
▶
Replace the PCB.
▶
Replace the control electrode (D.146, D.147).
Installation and maintenance instructions 0020328022_02