128
5790 733 - 07
Vitocrossal 300 CA3 Series 2.5 to 6.0 Installation/Service
Function Description
Heating Circuit Control
Only for single boiler and cascade control units
Brief description
H
The control unit features control circuits for one heating
circuit without mixing valve A1 (heating circuit 1) and
two heating circuits with mixing valve M2 (heating
circuit 2) and M3 (heating circuit 3).
H
The set supply temperature of each boiler is determined
from the following coding:
– Outdoor temperature
– Set room temperature
– Operating mode
– Heating curve slope and shift
H
The supply temperature of the heating circuit without
mixing valve corresponds to the common system supply
temperature.
H
The supply temperature of the heating circuits with
mixing valve is regulated by the stepped opening or
closing of the mixing valves.
The mixing valve motor control changes the actuating
and pause times subject to the control differential
(control
deviation).
Functions
The heating circuit without mixing valve is subject to
the boiler water temperature and its control range limits.
The heating circuit pump is the only actuator.
The supply temperature of the heating circuits with
mixing valve is captured by the supply temperature sensor
of the relevant heating circuit.
H
Upper control limit:
Electronic maximum supply temperature limit
coding address “c6” in the “Heating circuit...” group.
H
Lower control range limit:
Electronic minimum supply temperature limit
coding address “c5” in the “Heating circuit...” group.
Time program
The control unit switches over according to the time
program. In the “Heating and DHW” operating program,
the control unit switches between “Central heating with
standard room temperature” and “Central heating with
reduced room temperature”.
Every operating mode has its own set level. 4 time phases
per day can be selected.
Outdoor temperature
A heating curve must be set for matching the control
unit to the building and the heating system.
The heating curve characteristics determine the set boiler
water temperature subject to outdoor temperature.
The control unit uses an average outdoor temperature.
This comprises the actual and the adjusted outdoor
temperature.
Room temperature
In conjunction with a remote control and room
temperature hook-up (coding “b0” in the “Heating
circuit...”) group:
Compared with the outdoor temperature, the room
temperature has a greater influence on the set boiler
water temperature (changed at coding “b2” in the
“Heating circuit...” group).
In conjunction with heating circuits with mixing valve:
For control differentials (actual value deviation) above
4°F (2 K) room temperature, the influence can be increased
further (coding “b6” in the “Heating circuit...” group):
H
Quick heat-up
The set room temperature must be raised by at least
4°F (2 K) by the following measures:
– Enabling comfort mode
– Changing from central heating with reduced
temperature to central heating with standard
temperature
– Start optimization (coding “b7” in the “Heating
circuit...” group) Quick heat-up will stop when the
set room temperature has been reached.
H
Quick setback
The set room temperature must be reduced by at least
4°F (2 K) by the following measures:
– Activating economy mode
– Changing from central heating with standard
temperature to central heating with reduced
temperature
– Shutdown time optimization (coding address “c1”
in the “Heating circuit...” group)
Quick setback ends when the set room temperature
has been reached.
