Operation Manual

109/180
Siemens Schweiz AG User Manual CE1U2354en
HVAC Products Buffer storage tank 23. August 2007
return temperature increase or return temperature decrease (to be selected on
operating line 4796). This is defined on operating line 4796.
In addition, the setting of the respective relay output is to be made as “Buffer diverting
valve Y15” in configuration “Relay output QX1, 2 ,3, 4” (operating lines 5890, 5891,
5892 and 5894) and the common return temperature sensor (B73) at BX.
The selected temperature differential defines the switch-on / off point of return diversion.
Selection of the buffer storage tank temperature sensor with which the return
temperature is compared in order to switch the return diversion based on the selected
temperature differentials.
Temperature decrease
If the consumers’ return temperature is higher than the temperature at the selected
sensor (operating line 4795), the return can be used to preheat the lower storage tank
section. As a result, the return temperature drops further which, in the case of a
condensing boiler, leads to higher efficiency.
Temperature increase
If the consumers’ return temperature is lower than the temperature at the selected
sensor (operating line 4795), the return temperature can be raised by diverting the
return through the lower storage tank section. As a result, the return temperature
increases.
Partial charging
Line no. Operating line
4800 Partial charging setpoint
By hydraulically decoupling the lower buffer storage tank section, the chargeable
storage volume is reduced. As a result, the upper storage tank section is charged in a
shorter period of time. The lower storage tank section is only charged when charging of
the upper section is completed.
As soon as the temperature acquired by the temperature sensor (B4/B42) reaches the
setpoint of partial charging, the diverting valve change over to “through-port” and the
rest of the storage tank is charged also.
For changeover, a fixed switching differential of ¼ °C is used.
If the slave pointer is higher than the adjusted setpoint of partial charging, charging to
the slave pointer value takes place.
Configuration:
Extra function QX…
(operating lines 5890…5894)
Return diverting valve Y15 in the buffer
storage tank
Sensor input BX…
(operating lines 5930…5933)
Buffer storage tank sensor B4 or B42
Temp diff on/off return div
Compar temp return div
Optg action return
diversion