Functions of the DHW circuit
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 | FB9 = ON, PU |
| 10 min | Stop parallel operation / 2 to 10 min |
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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.
6.9Priority circuit (Anl 4, 5, 6, 7, 8 and 11)
In many district heating systems with primary DHW heating, the allotted amount of water is 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
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
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 | OFF | FB8 = ON, select “In“ |
DHW circuit | 10 min | 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
