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Siemens Switzerland Ltd 
User manual RVS61.843 CE1U2355en_02 
HVAC Products  6 The settings in detail  23. November 2007 
The temperature differential at an outside temperature of -10 °C that is entered on this 
operating line is transformed to the current composite outside temperature. 
At an outside temperature of -10 °C, the flow temperature setpoint is reduced by the set 
value, and there is no more reduction at an outside temperature of 20 °C. 
 
T
TRL
Ta
20°C
 TVL
-10°C
 5801
 
 
 
TVL Flow temperature 
tRL Return temperature 
Ta  Outside temperature (OT) 
 
 
Important! 
Instead of entering the correct temperature differential at -10 °C, it is also possible to 
enter 0 as the temperature differential. In that case, the heating curve must be set for 
the return temperature setpoint. But this choice only exists for plants without mixing 
heating circuit. 
 
Parameter 5810 is active only if there is no buffer storage tank. 
 
In cooling mode, the parameter has no impact. In the case of return temperature 
control, the cooling curve must be based on the return temperature setpoint. 
 
Solar 
Line no.  Operating line 
5840  Solar controlling element 
Charging pump 
Diverting valve 
 
5841  External solar exchanger 
Jointly 
DHW storage tank 
Buffer  
 
 
In place of a collector pump and diverting valves for integrating the storage tanks, the 
solar plant can also be operated with charging pumps. 
When using a diverting valve, it is always only one heat exchanger that can be used at 
a time. Only alternative operation is possible. 
When using a charging pump, all heat exchangers can be used at the same time. 
Either parallel or alternative operation is possible. 
 
In the case of solar plants with 2 storage tanks, it must be selected whether the 
external heat exchanger shall be used for DHW and as a buffer storage tank, or 
exclusively for one of the two. 
 
 
 
 
Solar controlling element  
External solar exchanger