Function Description Constant Temperature Control Unit; Heating Mode; Dhw Heating; Weather-Compensated Control Unit - Viessmann Vitodens 222-F Installation And Service Instructions For Contractors

Function description
Constant temperature control unit
s
Fig. 78

Heating mode

The selected set boiler water temperature will be main-
tained when a demand is being raised by the room
thermostat and the heating program is set to DHW and
central heating " ".
G
The boiler water temperature will be maintained at the
default frost protection temperature when there is no
demand.

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.

Weather-compensated control unit

21°C
14°C
Boiler temperature
Fig. 79
120
°C
4 8
A
HC1
48 °C
The electronic temperature limiter inside the burner
control unit limits the boiler water temperature.
Flow temperature setting range: 20 to 74 °C.
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.