Bosch HPC 400 Operating Instructions Manual page 39

Cause or fault description Test procedure/Cause
A21 1001 –
A22
A23
A24
H01 5284 Warning Last thermal
disinfection failed
H01 5252 Warning Z1 Flow rate
between outdoor and indoor
unit restricted
H01 5253 Warning Z2 Flow rate
between outdoor and indoor
unit restricted
H01 5283 Alarm Z2 High pressure
sensor
H01 5292 Alarm Z1 High pressure
sensor
H01 5293 Alarm Z1 Low pressure
sensor
H01 5295 Alarm Condensation guard
H01 5375 Alarm Z1 Frost protection
active
H01 5377 Alarm Z2 Frost protection
active
H01 5451 Alarm Z1 Flow rate too low
during defrosting
H01 5455 Alarm Z2 Flow rate too low
during defrosting
H01 5463 Alarm Z1 Defrosting failed
H01 5501 Alarm Z2 Low pressure
sensor
Table 49
HPC 400
No BUS connection between HPC 400
and CR 10 or CR 10 H in the
corresponding heating circuit (A22:
heating circuit 2, ..., A24: heating
circuit 4).
Check if water is possibly being drawn
from the DHW cylinder constantly due to
taps being open during thermal
disinfection.
Check whether the particle filter is dirty. ▶ Clean the filter
Check whether the particle filter is dirty. ▶ Clean the filter
Check whether the outdoor unit is dirty
(particularly the evaporator and fan)
Check whether the outdoor unit is dirty
(particularly the evaporator and fan)
Check whether the outdoor unit is dirty
(particularly the evaporator and fan)
Moisture has accumulated on the supply
pipes because the flow is too cold.
The temperature in the condenser is too
low. Pumps and possibly the heat pump
are switched on automatically.
The temperature in the condenser is too
low. Pumps and possibly the heat pump
are switched on automatically.
Check whether the filter is dirty.
Check whether the filter is dirty.
Check whether the outdoor unit is dirty.
Check the evaporator in particular for
dirt.
Check whether the outdoor unit is dirty
(particularly the evaporator and fan)
Eliminate fault | 39
Corrective measure
▶ Check that the user interface is
correctly seated in its wall bracket.
▶ Take action to stop water being
drawn constantly or change the time
at which thermal disinfection is
carried out.
▶ Clean the outdoor unit
▶ Clean the outdoor unit
▶ Clean the outdoor unit
▶ Wait until the moisture has dried.
Then press the rotary selector to
acknowledge the alarm on the HMI.
▶ If the alarm is issued again, call a
contractor. ( The lowest permitted
flow temperature will have to be
increased. This is a setting in the
service menu)
The heating system should not be
switched off during the heating period.
The heating system should not be
switched off during the heating period.
▶ Cleaning the filter
▶ Cleaning the filter
▶ Clean the outdoor unit (particularly
the evaporator)
▶ Clean the outdoor unit
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