Function Description; Weather-Compensated Control Unit - Viessmann Vitocrossal 300 Service Instructions For Contractors

Weather-compensated control unit

Boiler temperature
Heating
DHW
Solar energy
Information
Select with
Heating mode
The control unit determines a set boiler
water temperature subject to outside
temperature or room temperature (if a
room temperature-dependent remote
control is connected) and to the slope/
level of the heating curve.
The determined set boiler water temper-
ature is transferred to the burner control
unit. From the set and actual boiler water
temperatures, the burner control unit cal-
culates the modulation level and regu-
lates the burner accordingly.
DHW heating
The burner, the circulation pump and the
three-way valve are started or changed
over, if the cylinder temperature lies 2.5
K below the set cylinder temperature.
48 °C
(
The electronic temperature limiter inside
the burner control unit limits the boiler
water temperature.
The set boiler water temperature is
adjusted 20 K higher than the set DHW
temperature (adjustable via coding
address "60"). The burner will be
switched OFF and the circulation pump
run-on time will begin, if the actual cylin-
der temperature exceeds the set cylinder
temperature by 2.5 K.

Function description

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