Viessmann VITOTRONIC300 Installation And Service Instructions Manual page 83

Vitotronic 300, GW2B Installation and Service
Heating Circuit Control
Supply temperature control
Outside temperature
Legend
A Max. boiler water temperature
B Slope = 1.8 for heating circuit without mixing valve
C Slope = 1.2 for heating circuit with mixing valve
D Boiler water temperature (with a differential
temperature = 8 K)
E Lower boiler water temperature, defaulted by the
boiler coding card
Legend
A Heating curve for operation with standard room
temperature
B Heating curve for operation with reduced room
temperature
(continued)
Differential temperature:
The differential temperature is adjustable via coding
address "9F" in the "General" group, factory set condition
8 K.
The differential temperature is the value by which the
common supply temperature should be higher than the
highest currently required supply temperature of the
heating circuit with mixing valve.
H System with only one heating circuit with mixing valve:
H System with heating circuit and heating circuits with
Raising the reduced room temperature
During operation with reduced room temperature, the
reduced set room temperature can be automatically raised
subject to the outside temperature. The temperature
is raised in accordance with the selected heating curve,
but no higher than the set standard room temperature.
The outside temperature limits for the start and end of the
temperature raising can be adjusted via coding addresses
"F8" and "F9" in the "Heating circuit..." group.
Reducing the heat-up time
During the transition from operation with reduced room
temperature to operation with standard room temperature,
the boiler water or supply temperature will be raised in
accordance with the selected heating curve. The boiler
water or supply temperature increase can be automatically
raised.
The value and duration of the additional increase of the
set boiler water or supply temperature can be adjusted
in coding addresses "FA" and "Fb" in the "Heating
circuit..." group.
Outside temp.
The set boiler water temperature is regulated
automatically to 8 K above the set supply temperature
of the heating circuit with mixing valve.
mixing valve:
The set boiler water temperature operates in accordance
with its own heating curve. The differential temperature
of 8 K towards the set supply temperature of the
heating circuits with mixing valve is set at the factory.
Function Description
83