Viessmann VITODENS 300-W, Service Manual

Page: 91 / 124

L DHW only
G Heating and DHW
M Party mode
N Economy mode
b / a Setting values
d Confirmation
c Information
e Standard settings (Reset)
Heating operation
The control unit determines a set boil-
er water temperature subject to out-
side temperature or room temperature
(if a room temperature-dependent
remote control is connected) and to
the slope/level of the heating curve. The determined set boiler water tem-
perature is transferred 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 accord-
ingly.
The electronic temperature limiter
inside the burner control unit limits the
boiler water temperature to 82 °C.
DHW heating
The burner, the circulation pump and
the three-way valve are started or
changed over, if the cylinder tempera-
ture lies 2.5 K below the set cylinder
temperature. The set boiler water temperature is
adjusted 20 K higher than the set
DHW temperature (adjustable via
coding address "60"). 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.
Boosting DHW heating
The booster heating function is acti-
vated if a switching period is selected
for the fourth time phase. The set temperature value for the
heating boost is adjustable in coding
address "58".
Weather-compensated control unit
(cont.)
91
Function description
5692
673
GB