Viessmann Vitocrossal 300 CA3 2.5 Installation And Service Instructions Manual page 130

Function Description
Heating Circuit Control
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 = 15°F (8 K)]
E Lower boiler water temperature, defaulted by the
boiler coding card
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 = 15°F (8 K)]
E Lower common supply temperature
130
(continued)
Supply temperature control single boiler control unit
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 minimum value by
which the boiler water 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
Supply temperature control cascade control unit
Differential temperature:
The differential temperature can be set at coding "9f"
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
Vitocrossal 300 CA3 Series 2.5 to 6.0 Installation/Service
The set boiler water temperature will be automatically
regulated to 15°F (8 K) above the set supply temperature.
heating circuit with mixing valve:
The set boiler water temperature operates in
accordance with its own heating curve. The differential
temperature of 15°F (8 K) towards the set supply
temperature is set at the factory.
in the "General" group, factory set condition 15°F (8 K).
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.