Viessmann Vitocrossal 300 CA3 2.5 Installation And Service Instructions Manual page 131

Vitocrossal 300 CA3 Series 2.5 to 6.0 Installation/Service
Heating Circuit Control
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
Example using the settings in the factory set condition
Legend
A Start of operation with standard room temperature
B Set boiler water or supply temperature in accordance
with the selected heating curve
C Set boiler water or supply temperature in accordance
with coding "fa":
122°F (50°C) + 20% = 146°F (60°C)
D Duration of operation with higher boiler water or set
supply temperature in accordance with coding
"fb": 60 min
(continued)
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 set in coding "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 for the additional raising of the
boiler water temperature or set supply temperature can
be set in coding "fa" and "fb" in the "Heating circuit..."
group.
Control sequence
Mixing valve circuit
The mixing valve motor will not be switched within the
"neutral zone" ±2°F (±1 K).
Supply temperature drops
(Set value -2°F (–1 K)
The mixing valve motor receives the signal "mixing valve
open". The signal duration lengthens with an increasing
control differential. The duration of pauses reduces with
an increasing control differential.
Supply temperature rises
(set value +2°F (+1 K)
The mixing valve motor receives the signal "mixing valve
close". The signal duration lengthens with an increasing
control differential. The duration of pauses reduces with
an increasing control differential.
Function Description
131