90 EB 5573-1 EN
Functions of the DHW circuit
7.2 DHW heating in the storage tank charging system
Start storage tank charging
WW
SF1
SF2
SLP
TLP
ZP
KW
VF
TLP Heat exchanger charging
pump
VF Flow sensor
SLP Storage tank charging
pump
SF1 Storage tank sensor 1
SF2 Storage tank sensor 2
ZP Circulation pump (DHW)
WW Hot water
KW Cold water
Fig. 8: Schematics of a storage tank charging system
The controller begins charging the storage tank when the water temperature measured at
storage tank sensor 1 falls below the 'DHW temperature set point' by 0.1°C. If the ow tem-
perature in the system exceeds the desired charging temperature, the controller tries to re-
duce the ow temperature in the heating circuit for up to three minutes before the exchanger
charging pump is activated together with the storage tank charging pump. When there is no
heating operation or when the ow temperature in the system is lower, the exchanger
charging pump is switched on immediately. If the temperature currently measured at storage
tank sensor 1 is reached at the ow sensor VF or after three minutes at the latest, the storage
tank charging pump is switched on. If a storage tank thermostat is used, the storage tank
charging pump is switched on when the temperature T = Charging temperature – 5°C is
reached at the ow sensor VF.
Note:
The 'DHW temperature set point' is to be regarded in relation to the charging tem-
perature if a storage tank thermostat is used.
When the ow sensor VF4 is activated, the set point in the heat exchanger circuit is inu-
enced by the system deviation in the storage tank charging circuit upon activation of the stor-
age tank charging pump: if the temperature measured at ow sensor VF4 is lower than the
desired 'Charging temperature', the set point in the heat exchanger circuit is increased in
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