Function Description; Constant Temperature Control Unit - Viessmann Vitodens 222-F B2TA Installation And Service Instructions Manual

Constant temperature control unit

s
Heating mode
The selected set boiler water tempera-
ture will be maintained 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.
°C
4 8
A
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 temperature 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 temperature exceeds
the set cylinder temperature by 2.5 K.

Function description

149