Viessmann VITOTRONIC 200 Installation And Service Instructions Manual page 61

Vitotronic 200, HO1B and 300-K, MW2C Installation/Service
Heating Circuit Control Unit of the Vitotronic 300-K
Outdoor temperature
Legend
A Maximum supply temperature limit (coding "37"
in the "Cascade" group)
B Slope = 1.8 for heating circuit without mixing valve
C Slope = 1.2 for heating circuit with mixing valve
D Common supply temperature (at a differential
temperature = 8 K)
E Lower common supply temperature
Example using the settings in the factory set condition
Legend
A Heating curve for operation with standard room
temperature
B Heating curve for operation with reduced room
temperature
Function Description, Vitotronic 200/300-K
Supply temperature control
Differential temperature:
The differential temperature can be set at coding
"9f" in the "General" group, factory set condition 15°F
(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 without mixing valve and
Raising the reduced room temperature
During operation with reduced room temperature, the
reduced set room temperature can be automatically
raised subject to the outdoor temperature.
The temperature is raised in accordance with the selected
heating curve, but no higher than the set standard room
temperature.
The outdoor temperature limits for the start and end of
temperature raising can be adjusted at coding "f8" and
"f9".
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
codings "fa" and "fb".
Outdoor temp.
(continued)
The common set supply temperature is regulated
automatically to 15°F (8 K) above the set supply
temperature of the heating circuit with mixing valve.
heating circuits with mixing valve:
The common set supply temperature operates in
accordance with its own heating curve. The differential
temperature of 15°F (8 K) towards the set supply
temperature of the heating circuits with mixing valve
is set at the factory.
61