Function Description Weather-Compensated Control Unit; Heating Mode; Dhw Heating; Boosting Dhw Heating - Viessmann VITOCROSSAL Service Instructions Manual

Weather-compensated control unit
21°C
14°C
Boiler temperature
Fig. 44

Heating mode

The control unit determines a set boiler water tempera-
ture subject to outside temperature or room tempera-
ture (if a room temperature-dependent remote control
is connected) and to the slope
curve.
The determined set boiler water temperature is trans-
ferred to the burner control unit. From the set and
actual boiler water temperatures, the burner control
unit calculates the modulation level and regulates the
burner accordingly.

DHW heating

The burner and the circulation pump for cylinder heat-
ing are started if the cylinder temperature during the
cylinder enable time lies 2.5 K below the set cylinder
temperature.

Boosting DHW heating

This function is activated by specifying a second set
DHW temperature via parameter/coding address 58 in
the "DHW" group and activating the fourth DHW time
phase for DHW heating.
HC1
48 °C
level of the heating
/
The electronic temperature limiter inside the burner
control unit limits the boiler water temperature.
In the delivered condition, the set boiler water temper-
ature is 20 K higher than the set cylinder temperature
(adjustable via coding address "60"). If the actual cylin-
der temperature exceeds the set cylinder temperature
by 2.5 K, the burner shuts down and the circulation
pump run-on time begins.
Heating is boosted during the periods selected in this
time phase.
Function description
81