Appendix
0020213395_00 flexoTHERM exclusive Installation and maintenance instructions
45
Code
Meaning
Cause
Remedy
F.723
Building circuit: Pressure too low
–
Pressure loss in the building circuit
due to leaks or air pockets
–
Building circuit pressure sensor de-
fective
–
Check the building circuit for leaks
–
Top up with water, purge
–
Check the quality of the plug contact
on the PCB and on the cable har-
ness
–
Check that the pressure sensor is
working correctly
–
Replace the pressure sensor
F.724
Sensor fault: Fan unit 1 fan inlet
temp.
–
Sensor not connected or sensor in-
put has short-circuited
–
Check the sensor in the fan unit, and
replace if necessary
–
Replace the cable harness in the fan
unit
F.725
Sensor fault: Fan unit 1 brine flow
temp.
F.731
High pressure switch opened
–
Coolant pressure too high. The in-
tegrated high-pressure switch has
tripped at 46 bar (g) or 47 bar (abs)
–
Insufficient energy output via the
relevant condenser
–
Purging the building circuit
–
Insufficient volume flow as a result of
closing individual room controllers in
an underfloor heating system
–
Check that the dirt filter that is in
place is permeable
–
Refrigerant flow rate too low (e.g.
electronic expansion valve defective,
four-way valve mechanically blocked,
filter blocked). Inform Customer Ser-
vice.
–
VWL SA (cooling mode): Check the
fan unit for dirt
F.732
Compressor outlet temperature
too high
The compressor outlet temperature is
above 130 °C:
–
Application limits exceeded
–
EEV does not work or does not open
correctly
–
Coolant volume too low
–
Check the low-pressure sensor,
compressor inlet sensor and outlet
sensor
–
Check the EEV (does the EEV
move to the limit stop? Use the
sensor/actuator test)
–
Check the refrigerant volume (see
Technical data)
–
Carry out a leak-tightness test
F.733
Evaporation temperature too low
–
No flow rate in the environment cir-
cuit (heating mode)
–
Energy input too low in the environ-
ment circuit (heating mode) or build-
ing circuit (cooling mode)
–
Check the flow rate in the environ-
ment circuit
–
Check the dimensioning of the en-
vironment circuit (heating mode) for
ground/brine and groundwater/brine
–
If the building circuit contains ther-
mostatic radiator valves, check that
they are suitable for cooling mode
(cooling mode)
–
VWL_SA (heating mode)
–
Check the fan unit for dirt
–
Check the EEV (does the EEV
move to the limit stop? Use the
sensor/actuator test)
–
Check the low-pressure sensor and
compressor inlet sensor
F.734
Condensation temperature too low
–
Temperature in the building circuit
(heating mode) or environment cir-
cuit (cooling mode) too low for com-
pressor operation
–
Coolant volume too low
–
Check the EEV (does the EEV
move to the limit stop? Use the
sensor/actuator test)
–
Check the compressor inlet sensor,
high-pressure sensor and low-pres-
sure sensor
–
Check the refrigerant volume (see
Technical data)
–
Leak-tightness test
