Secondary Return Temperature (B71); Measurement; Handling Faults; Flow Temperature (B3) - Siemens RVL471 Basic Documentation

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• If there is a return temperature from a controller of the same segment available on the
data bus, it is used (only with plant type 1–x). No error message will be generated
since this is the normal state in interconnected plants
• However, if there is no return temperature available on the data bus, the return tem-
perature limitation functions will be deactivated and an error message generated
4.5

Secondary return temperature (B71)

4.5.1

Measurement

The secondary return temperature is acquired with a sensor having a sensing element
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6–x), together with the primary return temperature.
4.5.2

Handling faults

If there is a short-circuit or open-circuit in the measuring circuit, and if the controller
requires the return temperature, DRT limitation will be deactivated. An error message
will be generated
4.6 D.h.w. flow temperature (B3)
4.6.1 Measurement
The d.h.w. flow temperature is acquired with a sensor having a sensing element
LG-Ni 1000 
4.6.2 Handling faults
If there is a short-circuit or open-circuit in the measuring circuit, the d.h.w. will no longer
be heated. The charging pump is deactivated and the actuating device (slipper or seat
valve) is shut.
An error message will be generated.
4.7 D.h.w. storage tank temperature (B31, B32)
4.7.1 Measurement
The storage tank temperature can be acquired as follows:
• With one or 2 sensors having a sensing element LG-Ni 1000  RU
• With one or 2 thermostats
This means that there are 2 measuring circuits.
4.7.2 Handling faults
The controller's response to faults in the measuring circuits depends on the type of
d.h.w. demand (setting on operating line 126):
• One d.h.w. storage tank temperature sensor (operating line 126 = 0):
In the event of a short-circuit or open-circuit in one of the 2 measuring circuits, the
controller continues to work with the other measuring circuit, if possible. An error mes-
sage will not be generated.
Basic Documentation RVL471
4 Acquisition of measured values
CE1P2524E
23.10.2002