Appendix
0020213394_01 flexoTHERM exclusive Installation and maintenance instructions
51
Code
Meaning
Cause
Remedy
F.733
Evaporation temperature too low
–
No flow rate in the environment
circuit (heating mode)
–
Energy input too low in the envir-
onment circuit (heating mode) or
building 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.735
Evaporation temperature too high
–
Temperature in the environment
circuit (heating mode) or building
circuit (cooling mode) too high for
compressor operation
–
Feeding of external heat into the
environment circuit
–
Reduce or stop the external heat
that is entering
–
Check the de-icer (does it heat
up even though it is
Off
in the
sensor/actuator test?)
–
Check the EEV (does the EEV
move to the limit stop? Use the
sensor/actuator test)
–
Check the compressor inlet sensor
and low-pressure sensor
F.740
Environment cir. inlet temperature
too low
–
Inlet temperature in the environment
circuit too low for the compressor to
start for heating:
–
Air/brine: Environment circuit inlet
temperature < -28 °C
–
Ground/brine: Environment circuit
inlet temperature < -7 °C
–
Groundwater/brine: Groundwater
inlet temperature < 2 °C
–
Check the dimensioning of the envir-
onment circuit
–
Check the sensors
F.741
Building circuit inlet Return tem-
perature too low
–
Return temperature in the building
circuit too low for the compressor to
start
Heating:
–
Return temperature < 5 °C
Cooling:
–
Return temperature < 10 °C
–
Heating: Check that the four-way
valve functions correctly
F.742
Environment cir. inlet temperature
too high
–
Inlet temperature in the environment
circuit too high for the compressor to
start
–
Brine inlet temperature > 50 °C
–
Feeding of external heat into the
environment circuit
–
Heating: Check that the four-way
valve functions correctly
–
Check the environment circuit
–
Check the sensors
–
Reduce or stop the external heat
that is entering
F.743
Building circuit inlet Return tem-
perature too high
–
Return temperature in the building
circuit too high for the compressor to
start
Heating:
–
Return temperature > 55 °C to 60 °C
(depending on the brine inlet temper-
ature)
Cooling:
–
Return temperature > 35 °C
–
Cooling: Check that the four-way
valve functions correctly
–
Check the sensors
