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Once a parallel pump operation cycle has been activated and the time for
Stop parallel opera
-
tion
has elapsed, system deviations greater than 5 °C cause the controller to suspend parallel
operation for 10 minutes and to apply priority operation.
Function
WE Configuration
Parallel pump operation OFF
10 min
FB9 = ON, PU
Stop parallel operation / 2 to 10 min
Note!
In system Anl 9, the control valve of the underfloor heating circuit is always closed with the
function block setting FB9 = OFF. With the setting FB9 = ON, select “PU“ to ensure it remains in
control operation even the parallel operation has been interrupted due to system deviations.
6.9 Priority circuit (Anl 4, 5, 6, 7, 8 and 11)
In many district heatingsystems with primary DHW heating,the allotted amount of wateris only
intended to supply the heating system. As a result, the capacity required for DHW heating
needs to be taken from the heating system when great heating loads occur; and this, until DHW
heating has been concluded.
Nevertheless, heating operation is not simply to be interrupted. Only the amount of energy re-
quired for DHW heating is to be deducted. This can be achieved by using the priority functions
Reverse control and Set-back operation.
6.9.1 Reverse control
The capacity demand of the heating circuit is reduced when there is a system deviation of more
than 5 °C in the DHW circuit. This is achieved by the three-step output of the DHW circuit work
-
ing in the opposite direction compared to the heating circuit control valve.
The amount of time in which the priority for the DHW circuit is given is set in the
Priority in case
of deviation
parameter.
Function
WE Configuration
Priority for
DHW circuit
OFF
10 min
FB8 = ON, select “In“
Priority in case of deviation / 2 to 10 min
6.9.2 Set-back operation
The heating circuit is set back to reduced operation for 20 minutes when a system deviation of
more than 5 °C arises in the DHW circuit. Its capacity demand is reduced by the value in
EB 5476 EN 55
Functions of the DHW circuit