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Siemens Heating and D.h.w. Controller RVL481 CE1P2541en
Building Technologies 18 Function block "D.h.w. priority and flow temperature setpoint" 20.05.2008
18 Function block "D.h.w. priority and
flow temperature setpoint"
On this function block, the kind of d.h.w. priority (absolute, shifting, or parallel) and the
generation of the common flow temperature setpoint (maximum selection, d.h.w.) are set.
18.1 Operating line
Line Function, parameter Factory setting (range) Unit
124 D.h.w. priority, flow temperature setpoint 0 (0…4)
18.2 Settings
Operating line
124
D.h.w. priority Flow temperature setpoint according to
0 Absolute D.h.w.
1 Shifting D.h.w.
2 Shifting Maximum selection
3 None (parallel) D.h.w.
4 None (parallel) Maximum selection
18.3 D.h.w. priority
Depending on the capacity of the heat source, it may be practical to reduce the amount
of heat drawn by the heating circuit(s) during d.h.w. heating, thus ensuring that the
required d.h.w. temperature will be reached more quickly. This means that d.h.w. heat-
ing is given priority over space heating.
For this purpose, the controller offers 3 types of d.h.w. priority:
• Absolute priority
• Shifting priority
• No priority (parallel operation)
In the case of plants using a changeover
valve (plant types x–3), absolute priority is
always present. In that case, selection of the kind of priority has no impact.
The priority is provided by delivering locking signals. The effect of the locking signals is
described in section “25.4.7 Gain of locking signal".
18.3.1 Absolute priority
During d.h.w. heating, the heating circuits are locked, that is, they receive no heat.
• Controller with no bus connection:
During d.h.w. heating, the controller sends an uncritical locking signal of 100 % to its
own heating circuit
• Controller with bus connection:
During d.h.w. heating, the controller signals the "Consumer master" that it presently
provides d.h.w. charging with absolute priority. The consumer master is the unit with
the same segment number as the controller with device number 1. The consumer
master then sends an uncritical locking signal of 100 % to all controllers in the same
segment. If the consumer master is in segment 0, the uncritical locking signal will be
delivered to all controllers in all segments.
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