Appendix
0020250180_00 geoTHERM Installation and maintenance instructions
37
Code Meaning
Cause
Remedy
F.723
Building circuit: Pressure too low
–
Pressure drop in the building circuit
due to leakages 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 harness
–
Check that the pressure sensor
works correctly
–
Replace the pressure sensor
F.726
Compressor protector switch opened
–
Compressor overheated, e.g. as
a result of operating outside of its
application limits
–
Maximum environmental temperature
of 40 °C exceeded for the heat pump
–
Compressor blocked due to mechan-
ical defect
–
Compressor blocked because the
pressure difference is too high when
switched on (> 3 bar)
–
Environmental temperatures fall
below 40 °C
–
Check the pressure difference
during the start-up attempt
F.730
Low pressure switch opened
–
Low-pressure switch input not
bridged (X22-8 to X22-11)
–
Replace the cable harness
F.731
High pressure switch opened
–
Refrigerant pressure too high. The
integrated high-pressure switch
tripped at 41.5 bar (g)
–
Insufficient energy output via the
relevant capacitors
–
Purging the building circuit
–
Insufficient volume flow as a
result of closing individual room
controls in an underfloor heating
system
–
Check the existing dirt filter for
penetrability
–
Refrigerant flow rate too low
(e.g. electronic expansion valve
defective, filter blocked)
F.732
Compressor outlet temperature too high
The compressor outlet temperature is
above 115 °C:
–
Application limits exceeded
–
EEV does not work or does not open
correctly
–
Refrigerant volume too low
–
Check the low-pressure sensor,
compressor inlet sensor and
compressor outlet sensor
–
Check the EEV (does the EEV
move to the limit stop? Use the
sensor/actuator test)
–
Check the refrigerant volume
(700 g)
–
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 envir-
onment circuit
–
Check the dimensioning of the
environment circuit (heating
mode)
–
If the building circuit contains
thermostatic valves, check that
they are suitable for cooling
mode (cooling mode)
–
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
–
Refrigerant 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-pressure sensor
–
Check the refrigerant volume
(700 g)
–
Leak-tightness test
