*****INTERNAL*****30 R_D proof- 26.10.2022 / 09:15:46- VaillantGroup\DOC-agt\Brand\VIH_QW_190_6\ENG\OI-II_GB_0020291525
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Installation and maintenance instructions 0020291525_04
Code
Meaning
Cause
Remedy
F.819
Freq. converter fault: Overheating
–
Internal overheating of the frequency
converter
–
Allow the frequency converter to cool
and restart the product
–
Check the frequency converter's air
route
–
Check that the fan is working cor-
rectly
–
The maximum environmental tem-
perature of the outdoor unit (46 °C)
has been exceeded.
F.820
Connection fault: Building circuit
pump
–
Pump does not report any signal
back to the heat pump
–
Check the cable to the pump for
defects and, if required, replace it
–
Replace the pump
F.821
Sensor fault: Immers. heater flow
temp.
–
The sensor is not connected or the
sensor input has short-circuited
–
Both of the flow temperature sensors
in the heat pump are defective
–
Check and, if required, replace the
sensor
–
Replace the wiring harness
F.823
Hot gas temperature switch open
–
The hot gas thermostat shuts down
the heat pump if the temperature
in the refrigerant circuit is too high.
Following a waiting period, the heat
pump attempts to start once more.
After three failed start attempts
in succession, a fault message is
displayed.
–
Max. refrigerant circuit temperature:
110 °C
–
Waiting period: 5 mins (after it first
occurs)
–
Waiting period: 30 mins (after it
occurs a second time and any other
time after that)
–
The fault counter is reset if both of
the following conditions are met:
–
Heat requirement without switch-
ing off prematurely
–
60 mins uninterrupted operation
–
Check the EEV
–
Replace the dirt filter in the refrigera-
tion circuit, if required
F.824
Building circuit : Brinepressure
too low
Note
Can only occur in conjunction with
an installed and activated intermedi-
ate heat exchanger set.
Fault refers to the outdoor unit's
brine pressure sensor.
–
Pressure loss in the building circuit
due to leakages or air pockets
–
Building circuit pressure sensor
defective
–
Check the building circuit for leaks
–
Top up with water, purge
–
Check the quality of the plug contact
on the PCB and on the wiring har-
ness
–
Check that the pressure sensor is
working correctly
–
Replace the pressure sensor
F.825
Sensor fault: Capac. inlet temp.
–
Refrigerant circuit temperature
sensor (vapour-forming) not con-
nected or the sensor input has short-
circuited
–
Check and, if required, replace the
sensor and cable
F.1100
Immersion heater: Safety cut-out
open
The safety cut-out on the electric back-
up heater is open due to:
–
Insufficient volume flow or air in the
building circuit
–
The immersion heater is operated
when the building circuit is not filled
–
Immersion heater operation at flow
temperatures above 89 °C trips the
safety fuse of the safety cut-out and
requires that the fuse be replaced
–
Feed-in of external heat into the
building circuit
–
Check the circulation in the building
circuit pump
–
If required, open the stopcocks
–
Replace the safety cut-out
–
Reduce or stop the external heat
that is entering
–
Check that the dirt filter that is in
place is permeable
F.1117
Compressor: Phase failure
–
Defective fuse
–
Incorrect electrical connections
–
Mains voltage too low
–
Compressor/low tariff power supply
not connected
–
Energy supply company lockout for
over three hours
–
Check the fuse
–
Checking the electrical connections
–
Check the voltage at the heat pump
electrical connection
–
Set the max. duration of the ESCO
anti-cycling time to at least three or
more hours
