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Siemens Switzerland Ltd 
User manual RVS61.843 CE1U2355en_02 
HVAC Products  6 The settings in detail  23. November 2007 
Heat exchanger outside the storage tank, with 
primary controller. 
The controller calculates the charging pump’s speed 
required to ensure that the charging temperature 
acquired by sensor B35 is 2 K above the DHW 
setpoint. In this case, primary controller sensor B35 
must be located in the intermediate circuit. 
If B36 is connected as well, B35 must be positioned 
as the primary controller sensor. In this case, the 
controller calculates the speed required to ensure that 
the DHW setpoint + charging increase acquired by 
sensor B35 is achieved. 
 
2358A34
B3
Q3
B31
B36
Q33
B35
 
 
Speed control of intermediate circuit pump Q33  
 
The controller calculates the speed of the intermediate circuit pump required to ensure 
that the return temperature acquired by sensor B36 is 2 K above the DHW setpoint. 
If no B36 is connected, sensor B35 is used to make the calculation. 
If no valid sensor is connected, the pump speed is not controlled. 
 
 
6.17 Instantaneous DHW heater 
 
Summary 
2358A31
Y33
Q34
B38B39
FS
 
The controller supports DHW heating via 
an external heat exchanger. The heating 
energy required is delivered by the buffer 
storage tank. 
A speed-controlled or single-speed pump 
plus mixing valve are used to supply heat 
to the DHW circuit, depending on 
demand. 
 
Setpoints 
Line no.  Operating line 
5406  Min setp diff to tank temp 
 
The maximum DHW temperature setpoint controlled is the current storage tank 
temperature minus the setpoint differential that can be adjusted here. 
 
Speed-controlled pump 
Line no.  Operating line 
5530  Pump speed min  
 
The minimum speed of the pump for instantaneous DHW heater can be defined. It is 
thus possible to negate the lowest pump speeds, which cannot be properly controlled. 
 
Pump speed min