Viessmann Vitoplus 300 Service Instructions Manual page 85

Wall mounted oil fired condensing boiler for the combustion of low sulphur fuel oil din 51603-el-1 with integral boiler control unit

Table of Contents

Function description

Control

Heating mode

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 the

heating curve slope/level. The deter-

mined set boiler water temperature is

then transferred to the burner control

unit. The burner control unit deter-

mines the heat demand and accord-

ingly regulates the two-stage burner.

The burner control unit limits the boil-

er water temperature: by means of the

control thermostat to 74 °C; by the

electronic temperature controller to 82

°C. The temperature limiter in the

safety chain locks out the burner con-

trol unit at a boiler water temperature

of 100 °C.

DHW heating

DHW heating will be enabled if the

cylinder temperature drops 2.5 K

below the set cylinder temperature.

The burner and the cylinder primary

pump are switched ON. In the deliv-

ered condition, the set boiler water

temperature lies 20 K above the set

cylinder temperature. The burner will

be switched OFF and the cylinder pri-

mary pump run-on time will be acti-

vated, if the actual cylinder

temperature rises 2.5 K above the set

cylinder temperature.

Table of Contents

Vp3a