Vaillant ecoTEC plus VUI Series, Installation And Maintenance Instructions Manual

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88
Installation and maintenance instructions 0020308121_04
Code/meaning Possible cause Measure
N.270
The temperature spread via
the secondary heat exchanger
(heating flow
–
domestic hot
water connection) is too high.
The unit switches from regulat-
ing to controlling until the cause
has been eliminated by cus-
tomer service.
Flow rate quantity set incor-
rectly on the cold water adjust-
ing valve (only on a product
with no factory-installed flow
rate limiter)
▶
Set the flow rate quantity on the cold water adjusting valve.
Diverter valve stepper motor is
defective
▶
Check the diverter valve's stepper motor for potential mechan-
ical or electrical damage.
Interruption in the diverter
valve's wiring harness
▶
Check whether the wiring harness to the stepper motor and to
the PCB is connected correctly.
Scale in the secondary heat
exchanger.
▶
Descale or, if required, replace the affected heat exchanger.
3-port diverter valve defective
▶
Check and, if required, replace the 3-port diverter valve.
Flow rate limiter defective
▶
Check and, if required, replace the flow rate limiter.
N.317
The signal for the volume flow
sensor in the domestic hot wa-
ter circuit is implausible.
Interruption in the wiring har-
ness
▶
Check the wiring harness including all plug connections and, if
required, replace it.
Volume flow sensor in the do-
mestic hot water circuit defect-
ive
▶
Replace the volume flow sensor in the domestic hot water cir-
cuit.
N.319
The unit's internal bypass valve
is blocked.
Bypass valve dirty
▶
Clean the bypass valve.
Bypass valve defective
▶
Replace the bypass valve.
N.324
The electrical connection to the
pump has been interrupted.
Open circuit in wiring harness
(LIN cable)
▶
Check the wiring harness (LIN cable).
N.343
The signal for the air-mass flow
sensor is not plausible. If the
sensor set for the air-mass flow
is connected and there is feed-
back, but the values are im-
plausible, the unit works in limp
home mode.
Plug for air-mass flow sensor
loose/not plugged in
▶
Check the plug and the plug connection for the air-mass flow
sensor.
Plug on PCB loose/not plugged
in
▶
Check the plug and the plug connection.
Interruption in the wiring har-
ness
▶
Check the wiring harness including all plug connections and, if
required, replace it.
Measurement discrepancy too
high. Air-mass flow sensor dirty.
▶
Check the air-mass flow sensor for dirt.
You exit the measuring range
permanently. Air-mass flow
sensor defective
▶
Replace the entire air intake pipe.
PCB defective
▶
Replace the PCB.
L Wiring diagram
Note
The slot for the X13 connection is product-dependent and may not be present.