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7 System-wide functions
7.1 Automatic summer time/winter time changeover
The clock isautomatically adjusted on thelast Sunday in Marchat 2.00h and on thelast Sunday
in October at 3.00h.
Function
WE Configuration
Summer time/winter time changeover ON FB5 = ON
7.2 Frost protection
When outdoor temperatures below 3 °C occur, the heating circulation pumps UP1 andUP2 are
switched on. The controllers regulates the temperature to a flow temperature set point of 20 °C.
The circulation pump for the DHW circuit is likewise switched on. Outside the DHW heating
times-of-use, the temperature in the DHW storage tank is additionally kept at 5 °C, provided a
storage tank thermostat is not used. In conjunction with a storage tank thermostat, the frost pro-
tection function does not work outside the times-of-use.
Note!
The frost protectionfunction is not activated whenmanual mode is selectedat the mode switch.
7.3 Forced operation of the pumps
When the heating circuit pumps have not been activated for 24 hours, forced operation of the
pumps is started between 00.00h and 00.01h. This is done to avoid that the pumps get stuck
when they arenot operated for alonger period of time. Theforced operation of thestorage tank
or heat exchanger charging pump is operated between 00.01h and 00.02h.
7.4 Return flow temperature limitation
The temperature difference between the flow and return flow 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 whenthe flow temperatures are preset. The returnflow tem
-
perature can be limited either to a value depending on the outdoor temperature (variable) or to
a fixed set point. When the temperature measured at return flow sensor RüF exceeds the limit
value, the set point of the flow temperature (flow temperature of the heating system, charging
temperature) is reduced. As a result, the primary flow rate is reduced and the return flow tem
-
perature falls. The
Limiting factor
determines how stronglythe controller responds whenthe limit
values are exceeded in either direction.
EB 5476 EN 57
System-wide functions