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

Control unit

Weather-compensated 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 the slope/level of the heating 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.

Constant temperature heating mode

Upon demand by the room thermostat in the heating
and DHW " " operating program, the selected set
G
boiler water temperature is maintained.
The boiler water temperature will be held 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.

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.
The electronic temperature limiter inside the burner
control unit limits the boiler water temperature.
The electronic temperature limiter inside the burner
control unit limits the boiler water temperature.
Flow temperature setting range: 20 to 74
In the delivered condition, the set boiler water temper-
ature is 20 K above the set cylinder temperature
(adjustable via parameter/coding address 60 in the
"DHW" group). If the actual cylinder temperature
exceeds the set cylinder temperature by 2.5 K, the
burner shuts down and circulation pump run-on
begins.
Heating is boosted during the periods selected in this
time phase.
Function description
C.
º
103