EQJW146F002 EN
107
System-wide functions
Frost protection operation of a pump, a heating circuit or the DHW circuit is only active when
the frost protection icon is displayed.
System damage caused by frost!
In the stand-by mode ( ) fixed set point control without outdoor temperature sensor does not
include frost protection.
Do not switch off closed-loop operation for a long time during cold weather.
8.3 Forced pump operation
When the heating circuit pumps have not been activated for 24 hours, forced operation of
the pumps is started between 12.02 h and 12.03 h. This is done to avoid that the pumps get
stuck when they are not operated for long periods of time. In the DHW circuit, the circulation
pump is operated between 12.04 h and 12.05 h, the other pumps between 12.05 h and
12.06 h.
8.4 Return flow temperature limitation
The temperature difference between the flow and return flow in a network indicates how well
the energy is used: the greater the difference, the higher the efficiency. A return flow sensor
is sufficient to evaluate the temperature difference when the flow temperatures are pre-
defined. The return flow temperature can be limited either to a value depending on the out-
door temperature (variable) or to a fixed set point. When the return flow temperature mea-
sured at return flow sensor exceeds the limit, the flow temperature set point is reduced. When
the temperature measured at return flow sensor RüF exceeds the return flow temperature lim-
it, the set point of the flow temperature (flow temperature of the heating system, charging
temperature) is reduced. This causes the primary flow rate to be reduced and the return flow
temperature to drop. In systems Anl 2.x and 4.1, the 'Max. return flow temperature' parame-
ter (PA4 level) is used for limitation in the primary circuit during DHW heating if it is greater
than the parameter valid for the primary circuit.The KP (limiting factor) determines how
strongly the controller responds when the limits are exceeded in either direction (PI algo-
rithm).
If just the proportional component is to be implemented, set CO5 > F16-1. This allows the in-
tegral-action component in the return flow temperature limitation algorithm of all control cir-
Note
NOTICE
!
