Bosch Compress 3000 DW FOO Installation Instructions Manual page 12

12 | Appliance details
System basic theory
The refrigerant circuit is a closed system in which the
refrigerant R134a circulates as a heat transfer medium.
The evaporator transfers the heat from the air to the refrigerant
circuit, and the refrigerant evaporates into a gas.
The compressor compresses the refrigerant R134a, thus
increasing its temperature.
Then, the heat is transferred via a heat exchanger, also referred
to as a condenser, to the storage water tank. The refrigerant
R134a condenses in the process.
R134a flows through the expansion valve in a liquid state with
decreasing pressure, thus completing the cycle by being
routed back to the evaporator.
Brief overview of the appliance operation
Between 0 °C and 40 °C air temperature the appliance only
uses the economical heat pump cycle.
However, it is possible to manually turn on the electrical heater
together with the heat pump when the air is above 0 °C (One
shot boost). Once the set point is reached the boost is
automatically switched off.
Between -7 °C and 0 °C the appliance automatically switches
on the electrical heater together with heat pump cycle.
When the appliance has conditions to activate both electric and
compressor "FULL" is displayed at the HMI, alternating with the
top tank temperature.
When compressor and electrical heater are operating together,
the upper part of the tank will rise much faster than the lower
part, thus boosting the recovering time for the next hot water
load. Hence, with "FULL" active, if the top temperature gets
near the set point and the bottom is still rather at low
temperature, the appliance, will automatically switch off the
electrical heater and continues the heating with the heat pump
cycle only but "FULL" will remain being displayed.
After the electrical heater is switched off, it is normal that the
top temperature start to decrease slowly. Therefore, while
rising the bottom temperature by only using the heat pump
cycle and until the top temperature start to increase to set
point, the electrical heater will be switched on as many times as
required to keep the top near the set point.
Outside the air ambient range temperature, the unit operates
by only using the electrical heater.
6 720 808 869 (2014/06) Compress 3000 DW FOO