Basic Documentation

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Siemens Modular Heating Controller RMH760B CE1P3133en
Building Technologies 10 DHW heating 2017-09-29
During overrun, discharging protection switches the secondary pump off if:
DHW plant type
Condition for switching off
DHW 3
Flow temperature < storage tank temperature**
DHW 4
DHW 5
Flow temperature < storage tank temperature**
* If 2 storage tank sensors are used, the lower value will be considered
** If 2 storage tank sensors are used, the higher value will be considered
10.8.2 Limitation of the return temperature
With DHW plant types using a primary mixing valve, return temperature limitation can
be configured. This applies to plant types DHW 2, DHW 3, DHW 4 and DHW 6.
DHW 2
DHW 3, DHW 4
DHW 6
TFlPr
PrPu
VlvPr
TRt
3133S82
VlvPr
TFlSec
Sec
Pu
TRt
3133S83
VlvPr
FlSwi
TFlSec
TRt
3133S84
FlSwi
Flow switch (optional)
TFlSec
Secondary flow sensor
PrPu
Primary pump
TRt
Return sensor
SecPu
Secondary pump
VlvPr
Primary mixing valve
TFlPr
Primary flow sensor
If the return temperature exceeds the limit value, the flow temperature setpoint of the
DHW circuit will be lowered. If the return temperature drops below the limit value, the
reduction of the flow temperature setpoint will be negated again. Limitation operates as
an I-controller whose integral action time can be adjusted.
Main menu > Commissioning > Settings > … or
Main menu > Settings > DHW > Controller primary circuit
Operating line
Range
Factory setting
[Tn] return temp limitation max
0…60 min
30 min
The return temperature sensor must be assigned a terminal via "Extra configuration":
Main menu > Commissioning > Extra configuration > DHW > Inputs > Return sensor Assign
terminal
The function is to be activated via "Settings":
Main menu > Commissioning > Settings > … or
Main menu > Settings > DHW > Limitations
Operating line
Range
Factory setting
DHW return temp max
---- / 0…140 °C
---- °C
Legionella return temp max
----/ 0…140 °C
---- °C
This limitation is active provided a valid value has been set and the legionella function
is active. The limitation can be overridden by return temperature limitation in connection
with the legionella function.
Maximum limitation with DHW heating is constant, that is, independent of the outside
temperature.
Maximum limitation of
the return temperature
Extra configuration
Settings
Return temperature
limitation during DHW
heating