ation on the outdoor temperature sensors.
An a tive delayed outdoor temperature adaptation is signalized in the operating level by a
blinking outdoor temperature in the display. When you keep key pressed down, the Cal u-
lated outdoor temperature is shown in the display.
If the fun tion Time- ontrolled summer time operation (FB 3 = ON) is a tivated, the al ulated
outdoor temperature is not indi ated in the display.
4.8 Limitation of the return flow temperature
For an e onomi al operation of a distri t heating system, it is required that as mu h heat as
possible be extra ted from the heat transfer medium (water) ir ulating through the system. The
differen e in temperature between the flow and return flow in the network is used to indi ate
how mu h energy is being onsumed: a large differen e in temperature indi ates a high level of
energy effi ien y and a small differen e indi ates a low level of energy effi ien y. One return
flow temperature sensor is suffi ient to evaluate the differen e in temperature when the flow
temperature in the network is predetermined.
The fun tion is as follows: the return flow temperature an either be limited depending on the
outdoor temperature (variable) or by a fixed value. If the return flow temperature measured at
the return flow sensor RüF1 ex eeds the limit value al ulated from the set return flow hara -
teristi or the fixed limitation value by the value x, the respe tive al ulated or fixed set point
(flow temperature of heating, harging temperature) is redu ed by the value x, multiplied by re-
turn flow temperature limitation fa tor. As a result, the primary flow rate is redu ed with the ef-
fe t that the return flow temperature drops. Both the measured value of the Return flow tem-
perature and the set point (flow temperature of heating, harging temperature) blink in the dis-
play when a limitation ase o urs. The fun tion is already a tivated by the fun tion blo k set-
ting FB 20 = ON.
In system ode numbers 2 and 3 (drinking water heating implemented in the se ondary ir uit),
the ontroller swit hes during the heating up of drinking water over to the parameter Return
flow limitation temperature during drinking water heating from the return flow temperature
limitation value ( al ulated from the return flow temperature limitation hara teristi ). This en-
sures that the return flow limitation temperature in the heating ir uit an be held low in the sea-
sonal interim period.
In system ode number 4, a separate return flow temperature limitation in the drinking water
ir uit is additionally possible, provided FB 21 = ON.
System ode number 5 allows you to in lude the return flow temperature of the drinking water
ir uit. For this purpose, the return flow temperature sensor must be mounted in a return flow
pipe used in both ir uits, and the fun tion blo k FB 21 must be a tivated (ON). When FB 21 is
a tivated (ON), the parameter Return flow limitation temperature during drinking water heat-
ing (the temperature is adjustable at the ontroller) is a tivated. When drinking water is being
heated, the highest value from both return flow temperature limitation values (heating ir uit
and drinking water ir uit) is used for the limitation ontrol. When a limitation o urs, both the
set point in the heating ir uit and the set point in the drinking water ir uit are redu ed. If the
priority for drinking water through set-ba k operation is additionally a tivated (FB 8 = ON, set-
ting "Ab"), the redu ed heating ir uit set point is also further redu ed when a limitation o urs!
In system ode number 6, a return flow temperature limitation is only possible in the heating ir-
uit.
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