0020308118_05 Installation and maintenance instructions 95
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.
To Next Page
Loading...
Need help?
General