Viessmann Vitopend 100-W Installation And Service Instructions Manual page 86

Control unit
Function description
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.
86
(cont.)
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.