7.10 Flow rate/heat capacity limitation in Rk1
Flow rate/heat 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 SF2,
RF2 and without processing of an external demand 0 to 10 V. Particularly when a standard
-
ized signal is applied, a heat meter (flow meter) with high measuring accuracy is required.
Make sure that the controller is supplied with updated measured values in intervals of max.
5 seconds. In both cases (pulse or standardized signal), there are three different operating
situations:
4
A system with simultaneous room heating and DHW heating requires maximum energy.
4
A system with a fully charged storage tank which performs only room heating requires
less energy.
4
A system which suspends room heating during DHW heating requires less energy.
4
As a result, three different maximum limit values can be specified:
4
Max. limit value
to determine the absolute upper limit
4
Max. limit value heating
for exclusive operation of the room heating
4
Max. limit value DHW
for exclusive operation of the DHW heating
In all systems without DHW heating or without heating circuit, only the
Max. limit value
for
the flow rate or capacity can be set.
Note!
The limiting function is not available in systems Anl 10.
7.10.1 Limitation using pulse input
Depending on the operating situation, a heat meter with pulse output connected to input
WMZ/Bed (terminals 03/13) can be used to limit either the flow rate or the capacity in the
system. All limit values are given in the unit “pulses per hour“ [pulse/h]. As a result, the con
-
troller does not distinguish between a flow rate pulse signal or a capacity pulse signal. As
the displayed current pulse rate P [pulse/h] (–> Extended operating level, key number 1999)
is calculated depending on the interval between the received pulses, it is natural that the con
-
troller 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 value
, the flow set point of control
circuit Rk1 is reduced. How strongly the controller responds is determined by the
Limiting
factor
.
80 EB 5575 EN
System-wide functions
To Next Page
Loading...
