Vaillant geoTHERM Installation Instructions Manual page 105

Fault code Error text/description
84 Coolant pressure outside
the range
Error 29 has occurred
three times in a row
90 Heating system pressure
too low
Pressure <50 kPa (0.5 bar).
Heat pump shuts down
and goes into operation
automatically when the
pressure rises above
70 kPa (0.7 bar).
91 Brine pressure too low
Pressure < 20 kPa (0.2 bar)
Heat pump shuts down
and goes into operation
automatically when the
pressure rises above
40 kPa (0,4 bar).
11.4 Fault with permanent switch-off
Installation instructions geoTHERM 0020051574_04
Emergency
Possible cause
mode
possible
See Error 29.
Motor protection switch of the
compressor (Kriwan module) has
opened due to excessive winding
temperature.
For VWS/VWW 22/2 and 30/2
only:
Circuit breaker of the tempera-
ture monitor on the in-rush cur-
rent limiter faulty.
For VWS/VWW 38/2 and 46/2
only:
The fault relay on the in-rush cur-
rent limiter has responded.
The red LED on the in-rush cur-
rent limiter is flashing:
2x = Incorrect phase sequence
3x = Compressor motor overcur-
rent
4x = Thyristor module excess
temperature
5x = Low voltage/phase failure
6x = Min./max. power frequency
7x = No compressor connected
For VWS/VWW 38/2 and 46/2
only: Phase failure in combination
with fault 94.
_ Pressure drop in the heating sys-
tem due to leaks, air cushions or
a faulty expansion vessel.
Screw couplings at the rear of
the heat pump are not sealing
correctly.
Compression screw connections
on the 3-way diverter valve are
leaking.
possible (VWS only) Pressure drop in the
brine circuit due to leaks or air
cushions.
(VWS only) Brine pressure sensor
faulty.
Circuit breaker F1 on printed cir-
cuit board faulty.
Brine pressure switch fitted on-
site (VWS only) or limit thermo-
stat has opened.
Fault diagnosis and rectification
Solution
See Error 29.
Kriwan module closes of its own accord
after 30 minutes.
> Check bypass (ICL compressor) and
wiring. If the green LED on the in-rush
current limiter does not light up, the
temperature monitor circuit breaker is
faulty.
> Inform the factory customer service
department.
> Check whether the green LED on the
in-rush current limiter is lit. If the
green LED is not lit, there is no power
supply or the in-rush current limiter is
faulty.
> Check the power supply and restore.
> Check the in-rush current limiter and
inform the factory customer service
department if necessary.
> For VWS/VWW 38/2 and 46/2 only:
If the green LED lights up and red LED
is flashing, find the cause in the list of
flash codes above and rectify the
fault, and inform the factory customer
service department if necessary.
> See fault 94.
> Check the heating system for leaks.
> Top up water and bleed.
> Check the expansion vessel.
> Retighten screw couplings.
> Retighten the compression screw con-
nections on the 3-way diverter valve
for heating/cylinder charging.
> Check the brine circuit for leaks, top
up brine and bleed.
> Check the quality of plug contact on
the circuit board and on the cable har-
ness.
> Check the pressure sensor for correct
operation.
> Replace the pressure sensor.
> Check circuit breaker F1 and replace if
necessary.
> Check the brine pressure switch or
limit thermostat.
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