Basic Documentation

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Siemens Modular Heating Controller RMH760B CE1P3133en
Building Technologies 10 DHW heating 2017-09-29
10.4.4 Maintained secondary circuit
3133S92
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The maintained secondary circuit protects the storage tank's stratification by supplying
to the storage tank only water of higher temperatures (in accordance with the setpoint).
In addition, the maintained secondary circuit serves as an additional discharge
protection. But the "Discharge protection" function remains active because the
secondary pump is controlled based on the primary temperatures on the heating side.
The maintained secondary circuit can only be used in connection with DHW plant types
DHW 3 through DHW 5.
The maintained secondary circuit is activated via configuration of the mixing valve.
Main menu > Commissioning > Extra configuration > DHW > Outputs > Maintained sec temp 3-
pos > … or
Main menu > Commissioning > Extra configuration > DHW > Outputs > Maintained sec temp
modulating Assign terminal
For adapting the control parameters to the type of plant (actuator and controlled
system), the setting parameters to be used are the same as those used for mixing
valve control. They apply to both 3-position and DC 0…10 V actuators.
Main menu > Commissioning > Settings > … or
Main menu > Settings > DHW > Controller maint sec temp
Operating line
Range
Factory setting
Actuator running time
1…600 s
150 s
P-band Xp
1…100 K
50 K
Integral action time Tn
0…600 s
60 s
Maintained sec circuit delta
–20…20 K
0 K
The maintained secondary circuit controls to the following setpoint:
Setpoint maintained secondary circuit = DHW setpoint + maintained secondary circuit delta
On completion of storage tank charging, the secondary pump will be deactivated and
the mixing valve will fully close. If the secondary sensor is faulty, the mixing valve for
the maintained secondary circuit will be opened.
Extra configuration
Settings
Maintained secondary
circuit delta
Mixing valve function