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Siemens Building Technologies
HVAC Products
2. Full charging during the first DHW phase of the day:
DHW program
Nom.
Red. / frost.
Charging mode
Full charging
Recharging
7494f05E/0102
Charging of stratification storage tank with own DHW program
Full charging will be released during the first nominal phase of the DHW program:
Release of full charging = 1
If additional charging is required on the same day, only recharging takes place.
Release of full charging = 0
If no DHW program is selected on the QAA73... (continuously frost protection, reduced
or nominal level), following applies:
Release of full charging = 0
This means that recharging is continuously used.
• With compensation variant Bw = «RVA-dependent, fixed value control or
emergency operation»
Full charging is possible only if, for heating circuit 1, an external time switch is
connected to the LMU...
This will be predefined via parameterization.
KonfigRg1.Schaltuhr1:
0:
No time switch present, it is always recharging that is released
1:
A time switch for heating circuit 1 is connected to the room thermostat
If a time switch is used, full charging during the setback phases is released.
State of room thermostat input:
0:
Full charging released
1:
Recharging released
• With compensation variant Bw = «Locked»
Charging of the stratification storage tank is locked.
With the stratification storage tank, both sensors (for «TbwIst1» and «TbwIst2») must be
connected. If the sensor for «TbwIst1» has a short-circuit or open-circuit, the demands
for recharging and full charging of the stratification storage tank will be locked and the
relevant status code delivered.
If the sensor for «TbwIst2» has a short-circuit or open-circuit, full charging of the
stratification storage tank will no longer be possible. To have DHW available also if the
sensor for «TbwIst2» is faulty, only recharging with the help of the sensor for «TbwIst1»
is provided.
The boiler temperature setpoint is determined by boiler temperature setpoint =
BwSollwert + boost, whereby the minimum limitation is
boiler temperature setpoint = 50 °C + TuebBw.
Basic Documentation LMU54... / LMU64...
7 DHW control (BWR)
t
t
CC1P7494en
07.11.2002
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