Heating Circuit Control Unit Of The Vitotronic 300-K - Viessmann VITOTRONIC 200 Installation And Service Instructions Manual

Function Description, Vitotronic 200/300-K

Heating Circuit Control Unit of the Vitotronic 300-K

58
Vitotronic 200, HO1B and 300-K, MW2C Installation/Service
Brief description
H The control unit has 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 every heating circuit is
determined from the following coding:
– Outdoor temp
– 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
common supply 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 "c6" in the "Heating circuit..." group.
H Lower control range limit:
Electronic minimum supply temperature limit
Coding "c5" in the "Heating circuit..." group.
Time program
In accordance with 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 up 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.