Basic Documentation

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Siemens Modular Heating Controller RMH760B CE1P3133en
Building Technologies 10 DHW heating 2017-09-29
The impact of flow switch and PID controller is matched in a way that the actuator
travels to the new position as quickly as possible. After the flow switch has responded,
the control system will resume control of the actuator on the primary side.
The end of DHW consumption is also detected by the flow switch, and actuator Y1 on
the primary side will be driven to the fully closed position.
In contrast to plant types with storage tank, the circulation losses cannot be
compensated here via the storage tank, but must be continuously drawn from the
heating network.
When the flow switch indicates the end of DHW consumption, the primary valve will not
be fully closed for this reason. If the valve’s position exceeds the set "Min stroke with
flow signal", it will start to close until the minimum stroke is reached. From this position,
valve control is started. For this reason, the controller must be aware of externally
operated circulating pumps:
Main menu > Commissioning > Settings > … or
Main menu > Settings > DHW > DHW
Operating line
Range
Factory setting
External circulating pump
Yes / No
No
The assumption is made that the external circulating pump operates 24 hours a day.
Further setting choices for the circulating pump are described in subsection 10.11.3
"Circulating pump".
The cold water must join the DHW from the circulation pipe right by the heat exchanger.
If, for plant reasons, this is not possible, the "Min stroke with flow signal" must be set to
0 %.
10.5.4 Maximum charging time
The maximum charging time is also active with direct DHW heating. Subsection 10.4.3
"Maximum charging time" contains additional details on this function.
The controller is supplied with the function deactivated.
10.5.5 Legionella protection with direct DHW heating
During the time the legionella program is active, the circulating pump must operate.
For direct DHW heating, the information given in the following section " Legionella
protection".
If no circulating pump is used, it is recommended to deactivate the legionella function.
In that case, the legionella protection frequency must be set to "Never".
10.6 Legionella protection
The "Legionella protection" function can be an important measure aimed at preventing
the growth of legionella viruses.
However, the legionella program is
no guarantee for preventing the growth of legionella
viruses because these might occur in plant sections that the function cannot reach.
Flow switch with
circulating pump
Setting
Note
Notes