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Siemens Building Technologies
Basic Documentation RVL471
CE1P2524E
HVAC Products
13 Function block "Setpoint of return temperature limitation"
23.10.2002
When the integral reaches the value of zero, the minimum return temperature limitation
will be deactivated, in which case the critical locking signal is zero.
If minimum limitation of the return temperature is active, the display shows .
Minimum limitation of the return temperature can be deactivated.
Section “25.4.7 Gain of locking signal” provides information on who the critical locking
signal is sent to and how the consumers respond to it.
The minimum limit value is to be set on operating line 101. Setting --- = (inactive)
13.3.3
Mode of operation with a single device (with no bus)
252
4B
03e
Controller 1
Boiler controller
Controller 2
Plant type 1-1
Controller 2 generates a critical
locking signal which shuts the
heating circuit mixing valve and
deactivates the charging pump
With no possibility of minimum
return temperature limitation
Operating line 101 = 50 °C
return temperature sensor
connected
13.3.4
Mode of operation in interconnected plants
Controller 1
Plant type 5-0
Controller 2
Plant type 1-0
Controller 3
Plant type 1-1
Critical locking signal
Controller 2 shuts the
heating circuit mixing
valve
Controller 3 shuts the heating
circuit mixing valve and deacti-
vates the d.h.w. charging pump
LPB
25
24B0
7e
Setting operating
line101 = 50 °C,
return sensor connected
Setting operating line 101 = - - - , no own
return sensor connected
Setting operating line 101 = - - - , no own
return sensor connected
Critical locking signal
Controller 1
Boiler controller
Controller 2
Plant type 1-0
Controller 3
Plant type 1-0
Return temperature signal
Controller 2 limits the
return temperature
to 50 °C min.
LPB
252
4
B
08e
Setting operating line 101 = 50 °C,
return sensor connected
Setting operating line 101 = 40 °C, on own
return sensor connected
(With no possibility of
minimum limitation of
the return temperature)
Controller 3 limits the
return temperature
to 40 °C min.
The zone controller with its own return temperature sensor (plant type 1–x) passes the
return temperature to the other zone controllers in the same segment, which can provide
minimum limitation of the return temperature on a local basis, depending on the settings
made. This means they generate a critical locking signal internally. For response to criti-
cal locking signals, refer to section “25.4.7 Gain of locking signal“.
Variant 1 – central action
of limitation
Variant 2 – local action
of limitation
