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Note!
The function cannot be selected in systems Anl 4, 5 and 9 with solar system and in system
Anl 11 with VF3.
7.10 Flow rate/capacity limitation
Flow rate/capacity limitation can be implemented based on a pulse or standardized signal of
0/4 to 20 mA provided by the heat meter. This only applies in plants without solar system. Par
-
ticularly when a standardized signal is applied, a heat meter (flow meter) with high measuring
accuracy is required.
It must be ensured that the controller is supplied with updated measured values in intervals of
max. 5 seconds.
In system Anl 1, just the maximum limit for the flow rate or capacity can be entered.
7.10.1 Limitation using pulse input
A connected heat meter (terminals GND/15) with pulse output can be used to limit either the
flow rate or the capacity in the system.
Two different maximum limits can be set:
4
Maximum limit
4
Maximum limit for DHW
exclusively for DHW heating
All limit values are given in the unit “pulses per hour“ [pulse/h]. As a result, the controller does
not distinguish betweena flow rate pulsesignal or a capacitypulse signal. As the displayedcur-
rent pulse rate P [pulse/h] is calculated depending on the interval between the received pulses,
it is natural that the controller cannot react immediately to all rapid flow rate or capacity
changes which occur in the system.
When the pulse rate reaches the current
Max. limit
, the current flow set point is reduced. How
strongly the controller responds is determined by the
Limiting factor
.
In systems Anl 4 to 6 and 11, the control circuit with lowest set limit in the set point is always re
-
duced.
Example to determine the limit:
If a capacity of 30 kW is to be limited, the following limit value must be set for a heat meter with
an output of one pulse per kilowatt-hour:
P
30 kW
1KWh/pulse
30 pulse / h==
EB 5476 EN 61
System-wide functions