Boiler Function Description - Viessmann VITOTRONIC 300 Installation And Service Instructions Manual

Boiler function description

All parameters for the following functions are set on
the Vitotronic 100.
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 specified by the
Vitotronic 300.
For low temperature boilers, a minimum boiler water
■
temperature is specified via the coding card. This is
maintained to protect the boiler.
■ Low temperature boiler in conjunction with Therm-
Control temperature sensor or return temperature
sensor T1:
If the set boiler water temperature at the Therm-Con-
trol temperature sensor or at return temperature sen-
sor T1 ( ) is not reached, the set boiler water
aJA
temperature is increased.
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.
Control sequence
Boiler goes cold
The burner is started if the boiler water temperature
falls 2 K below the set boiler water temperature. The
burner starts its own monitoring program.
Note
The burner start may be delayed by a few minutes,
depending on the number of auxiliary circuits and the
combustion type.
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
Boiler heats up
Single stage burner:
■
The burner is stopped if the boiler water temperature
rises 2 K above the set boiler water temperature.
■ Two-stage or modulating burner:
The burner is stopped if the boiler water temperature
rises above the set boiler water temperature by the
shutdown differential.
The shutdown differential is set at parameter "13" in
the "Boiler" group.
Boiler function description
149