Pressure Switch And Overheating Protection; Function Test; Operating Temperatures; Operation Without The Outdoor Unit - Bosch Compress 3400i AWS Installation Manual
Indoor unit for air to water heat pump
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Operation without the outdoor unit (individual operation)
6.4
Pressure switch and overheating protection
The pressure monitor and overheating protection are only installed in
indoor units with integrated electric booster heater.
The pressure switch and overheating protection are connected in series.
Alarms or information triggered at the control unit indicate either that
the operating pressure is too low, or that the temperature of the electric
booster heater is too high.
NOTICE
Material damage from running dry!
When the primary circulation pump PC0 is operated for a long time when
the operating pressure is too low, it can be damaged.
▶ Eliminate any leaks in the system that are indicated when the
pressure switch is triggered.
The triggering of the pressure switch only blocks the electric booster
heater. The primary circulation pump PC0 and the outdoor unit can
continue to run if there is a risk of frost.
Pressure switch
The indoor unit has a pressure switch which triggers once the pressure in
the heating system falls below 0.5 bar. Once the pressure exceeds
0.5 bar, the pressure switch is automatically reset.
▶ Make sure that the expansion vessel and pressure relief valve are
configured for the indicated operating pressure, and check whether
an additional expansion vessel is necessary in the system.
▶ Check the system for leaks, and use a larger expansion vessel if
necessary.
▶ Slowly increase the pressure in the heating system by adding water
through the fill valve.
Overheating protection
The overheating protection triggers when the temperature of the electric
booster heater rises above 95 °C.
▶ Check the operating pressure.
▶ Check the heating and DHW settings.
▶ Reset the overheating protection. To do this, press the button on the
terminal box.
6.5
Function test
▶ Start the system according to the instructions for the control unit.
▶ Vent the system according to chapter 6.2.
▶ Test the active components of the system as described in the
instructions for the control unit.
▶ Check if the start conditions have been met for the outdoor unit.
▶ Check if there is a heating or hot water demand.
-or-
▶ Draw off DHW or increase the heating curve to generate demand (if
necessary, adjust the setting for Heating mode down if the outside
temperature is high).
▶ Check if the outdoor unit starts.
▶ Make sure that there are no current alarms (see instructions for the
control unit).
-or-
▶ Eliminate any faults according to the control unit instructions.
▶ Check the operating temperatures in accordance with the
instructions for the control unit.
20
6.5.1
Operating temperatures
The operating temperature check must be performed in heating mode
(not in DHW or cooling mode).
For optimum system operation, the flow rate in the heat pump and
heating system must be monitored. This check should be performed
when the heat pump is operating for more than 10 minutes and during
high compressor heating output.
The temperature differential for the heat pump must be set for the
different heating systems.
▶ With underfloor heating system 5 K as temp.diff. Setting heating.
▶ With radiators 8 K as temp.diff. Setting heating.
These settings are optimal for the heat pump.
Check the temperature differential at high compressor heating output:
▶ Open the diagnosis menu.
▶ Select Monitored values.
▶ Select Heat pump.
▶ Select Temperatures.
▶ Read the primary flow temperature (heat transfer medium out,
sensor TC3) and return temperature (heat transfer medium in,
sensor TC0) in heating mode. The flow temperature must be higher
than the return temperature.
▶ Calculate the difference TC3–TC0.
▶ Check whether the difference corresponds to the delta value set for
heating mode.
If the temperature differential is too large:
▶ Vent the heating system.
▶ Clean filters / strainers.
▶ Check pipe dimensions.
Temperature differential in the heating system
▶ Set the output at the heating pump PC1 so that the following
difference is achieved:
▶ With underfloor heating system: 5 K.
▶ With radiators: 8 K.
7
Operation without the outdoor unit (individual
operation)
The indoor unit can be started without the outdoor unit being connected,
for example if the outdoor unit is to be installed at a later date. This is
termed individual operation or stand-alone operation.
With individual operation, the indoor unit only uses the integrated or
external auxiliary heater for heating and DHW heating.
Commissioning in individual operation:
▶ In the «Heat pump» service menu, select the option «Stand-alone
mode» ( instructions for the control unit).
Compress 3400i AWS – 6721852066 (2023/01)
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