7 System-wide functions
7.1Automatic summer time/winter time changeover
The clock is automatically adjusted on the last Sunday in March at 2.00h and on the last Sunday in October at 3.00h.
Function | WE | Configuration |
Summer time/winter time changeover | ON | Co5 |
7.2Frost protection
The Frost protection function does not work in manual mode.
The heating system is automatically monitored for frost protection. The operation of a pump, a heating circuit or DHW circuit as a frost protection measure is indicated by 
on the display. If the outdoor temperature drops below 0 °C, the heating and circulation pumps are activated. The DHW storage tank is charged to 10 °C.
7.3Forced operation of the pumps
When the heating circuit pumps have not been activated for 24 hours, forced operation of the pumps is started between 12.00h and 12.01h. This is done to avoid that the pumps get stuck when they are not operated for a longer period of time. The forced operation of the storage tank or heat exchanger charging pump is operated between 12.01h and 12.02h.
7.4Return 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 when the flow temperatures are preset. The return flow 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 Limitation factor, 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 temperature falls. The set point reading (flow temperature of the heating system, charging temperature) blinks to indi- cate that a return flow limitation is active.
EB 5179 EN 59
