Vaillant geotherm exclusive Installation Instructions Manual page 75

Fault code Error text/description
22 Frost protection heat source
over. source outlet
Source outlet temperature T8
too low (< Freeze protect temp.
parameter in Menu A4)
27 Coolant pressure too high
The integrated high pressure
switch tripped at 30 bar (g).
The heat pump can start again
after a 60 minute wait at the
earliest.
28 Coolant pressure too low
The integral low pressure switch
has tripped at 1.25 bar (g).
29 Coolant pressure outside the
range
If the error occurs twice in a row
the heat pump cannot be started
until after 60 min. at the earliest.
Table 10.3 Temporary malfunctions (cont.)
geoTHERM exclusive VWS 0020051614_00 installation instructions
Troubleshooting and diagnosis 10
Possible cause
Heat source pump defective, temper-
ature sensor T8 defective.
Too low a volume flow in the heat
source circuit.
No/full dirt filter in source return line.
Air in brine circuit.
Heat consuming side using too little heat. Possible causes:
Air in the heating system.
Defective heating pump or pump out-
put has reduced.
Radiator heating without low loss
header or buffer cylinder.
Buffer cylinder, sensors VF1 and RF1
interchanged.
Too low a volume flow as a result of
closing individual room controllers in
an underfloor heating system. Brief
heating operation occurs after every
DHW charge if the outside tempera-
ture falls below the outside temp.
switch-off limit! The control system
checks if heating operation is re-
quired.
Domestic hot water cylinder with too
low a power input installed.
Existing dirt strainers clogged or in-
correctly dimensioned.
Stop valves closed.
Coolant flow rate too low (e.g. ther-
mal expansion valve TEV incorrectly
adjusted or defective).
Heat source providing too little heat. Possible causes:
(VWS only) Air in heat source circuit. Bleed the heat source circuit.
(VWS only) Brine pump defective or
pump output has reduced.
(VWS only) Not all circuits are circu-
lating equally. Recognisable by differ-
ent degrees of icing on individual
brine circuits.
Existing dirt strainers clogged or in-
correctly dimensioned.
Not all the required stop valves are
open.
Coolant flow rate too low (e.g. ther-
mal expansion valve TEV incorrectly
adjusted or defective).
Coolant pressure too high or too low,
all above-mentioned causes possible
Errors (27 and 28).
Solution
Check heat source flow rate.
Check the plug contact on the PCB and the cable
harness, check the sensor for correct position
and function (resistance measurement using VR
11 characteristics, see Appendix), replace sensor.
Check the volume flow of the well pump/brine
pump (optimum temp. difference approx. 3-5 K).
Clean the filter
Bleed the brine circuit.
Bleed the heating system.
Check pump, replace if necessary.
Check the system.
Check the sensor positions.
Check the system.
Check power input.
Clean dirt strainers.
Open all stop valves.
Check coolant circuit.
Check brine pump.
Adjust the brine circuits.
Clean dirt strainers.
Open all stop valves.
Check coolant circuit.
See Errors 27 and 28.
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