Function Description Control Unit; Heating Mode; Dhw Heating; Boosting Dhw Heating - Viessmann Vitoladens 300-W Installation And Service Instructions For Contractors

Function description
Control unit
21°C
14°C
Boiler temperature
Fig. 52

Heating mode

The control unit calculates a set boiler water tempera-
ture depending on the outside temperature and/or the
room temperature (if a room temperature-controlled
remote control facility is connected) and the slope/level
of the heating curve. The set boiler water temperature
determined is then transferred to the burner control
unit.

DHW heating

The burner, the circulation pump and the 3-way valve
are started or changed over if the cylinder temperature
lies 2.5 K below the set cylinder temperature.

Boosting DHW heating

This function is activated by specifying a second set
DHW temperature via coding address 58 in group
"DHW" and activating the fourth DHW phase for DHW
heating.
92
HC1
48 °C
The burner control unit determines the heat demand
and accordingly regulates the modulating burner. The
boiler water temperature is limited in the burner control
unit: to 74 °C by the temperature controller, and to
82 °C by the electronic temperature limiter. The tem-
perature limiter in the safety chain locks out the burner
control unit at 100 °C boiler water temperature.
In the delivered condition, the set boiler water temper-
ature is 20 K above the set cylinder temperature
(adjustable via coding address 60 in group "DHW").
The burner will be switched off and the circulation
pump run-on time will begin if the actual cylinder tem-
perature exceeds the set cylinder temperature by 2.5
K.
Heating is boosted during the periods selected in this
time phase.