Control Sequence For Burner Switching Hysteresis Of 4 K; Heating Circuit Control Unit; Brief Description; Functions - Viessmann VITOTRONIC 200 Installation And Service Instructions Manual

Boiler water temperature control
ON
OFF
+17
+3
set
-3
low average
heat demand heat demand
Fig.42

Control sequence for burner switching hysteresis of 4 K

Boiler goes cold
(Set value 2 K)
–
The burner start signal is set at the set boiler water
temperature 2 K. The burner starts its own monitor-
−
ing program.
The burner start may be delayed by a few minutes,
depending on the number of auxiliary circuits and the
combustion type.

Heating circuit control unit

Brief description

The control unit has control circuits for one heating
■
circuit without mixer A1 (heating circuit 1) and 2
heating circuits with mixer M2 (heating circuit 2) and
M3 (heating circuit 3).
■ The set flow temperature of each heating circuit is
determined from the following parameters:
Outside temperature
–
Set room temperature
–
– Operating mode
– Heating curve slope and level

Functions

The heating circuit without mixer is subject to the boiler
water temperature and its control range limits.
The heating circuit pump is the only actuator.
The flow temperature of the heating circuits with mixer
is captured by the flow temperature sensor of the rele-
vant heating circuit.
Time program
The control unit switches between "Central heating
with standard room temperature" and "Central heating
with reduced room temperature" in line with the time
program in the "Heating and DHW" operating pro-
gram.
(cont.)
Time
high
heat demand
Boiler heats up
(set value +2 K)
The burner shuts down.
Modulating burner:
The burner stop point is determined by the stop differ-
ential (coding address "13").
The flow temperature of the heating circuit without
■
mixer is equal to the boiler water temperature.
■ The flow temperature of the heating circuits with
mixer is regulated by the stepped opening or closing
of the mixers.
The mixer motor control changes the actuating and
pause times subject to the control differential (control
deviation).
Every operating mode has its own set level.
You can set up to 4 time phases.
Outside temperature
A heating curve must be set to adjust the control unit
to the building and the heating system.
The heating curve characteristics determine the set
boiler water temperature subject to outside tempera-
ture. The control unit regulates in line with an average
outside temperature. This is composed of the actual
and the adjusted outside temperature.
Function description
77