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Frost protection function
The boiler must be switched on to
ensure frost protection.
Boiler frost protection
Frost protection without outside
temperature sensor
If the boiler water temperature falls
below 8 °C the circulation pump starts,
and continues to run until 12 °C is ach-
ieved. The 3/2-way valve is in the heat-
ing circuit position.
If the temperature continues to fall to
below 5 °C the burner also starts, and
continues to run until the boiler water
temperature reaches 30 °C. The 3/2-
way valve switches to the DHW posi-
tion and heats the water to 57 °C.
Frost protection with connected out-
side temperature sensor
If the outside temperature falls
below 1 °C the circulation pump starts,
and continues to run until the outside
temperature reaches 3 °C.
If the boiler water temperature contin-
ues to fall, the burner also starts
below 5 °C, and continues to run until
the boiler water temperature reaches
30 °C. The 3/2-way valve switches to
the DHW position and heats the water
to 57 °C.
DHW cylinder frost protection
If the cylinder temperature falls
below 5 °C, the frost protection function
is enabled. The burner remains on until
the cylinder temperature reaches
7.5 °C.
Control unit
Function description
(cont.)
5837146