Boiler Water Temperature Control - Viessmann Vitotronic 200 Installation And Service Instructions For Contractors

Boiler water temperature control

Brief description
The boiler water temperature is regulated by starting
■
and stopping the burner or through modulation.
■ The set boiler water temperature is determined from
the following parameters:
– Set flow temperature of the heating circuits and
those connected via the LON
External demand
–
Set DHW temperature
–
■ For low temperature boilers, a minimum boiler water
temperature is specified via the coding card. This
must be maintained in order to protect the boiler.
Control functions
Capturing the boiler water temperature:
High limit safety cut-out STB (liquid expansion)
■
Temperature controller TR (liquid expansion)
■
■ Boiler water temperature sensor NTC 10 k
Upper control range limits
■ High limit safety cut-out STB 110/100 °C
Temperature controller TR 95/100/110 °C
■
Electronic maximum temperature limit:
■
Setting range: 20 to 127 °C
–
– Changes at parameter "06" in the "Boiler" group.
Boiler protection function: Therm-Control (start-up control)
■ For heating systems with distributor installed close to
the boiler
Conditions:
■
The boiler water flow rate must be able to be
reduced by at least 50 % in the start-up phase (e.g.
after a weekend shutdown).
■ Also affects the heating circuits.
Function
The Therm-Control sensor, installed near the return
■
connector, captures the return temperature.
■ The burner is ramped up to full load if the factory-
selected set temperature (specified by the coding
card) is not being achieved. The flow rate is reduced
via the mixer.
If the set temperature is exceeded, the mixers are
■
opened. The flow rate is always increased to 100 %.
Connection in heating systems without LON
■ Plug A1 of the Vitotronic is used as a switching
sÖ
contact for the Therm-Control.
Required parameter: "53:2" in the "General" group
■
Low temperature boilers in conjunction with Therm-
■
Control:
If the set temperature at Therm-Control sensor
is not reached, the set boiler water temperature is
increased.
When the DHW cylinder is heated, a set boiler water
■
temperature is specified that is 20 K higher than the
set DHW temperature (adjustable at parameter "06"
in the "DHW" group).
Lower control range limits
In standard mode and when frost protection is ena-
■
bled, the boiler water temperature will be regulated
subject to the respective boiler.
Ω
20 A1
20
N L
K
B
Fig. 45
A1 Closing of mixers
sÖ
Contactor relay, part no. 7814 681
A
Downstream heating circuit controller, switching
B
contact closed:
Signal for mixer CLOSE
Function description
A
close close close
1 2 n
aJA
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