Viessmann VITOTRONIC 100 Installation And Service Instructions Manual page 123

Boiler water temperature control
Functions
The boiler water temperature is
recorded by three sensors
separately, which are inserted into a
multiple sensor well:
H High limit safety cut−out (STB)
(liquid expansion)
H Control thermostat TR
(liquid expansion)
H Boiler water temperature sensor KTS
(change in resistance PT 500)
Upper control range limits
H High limit safety cut−out STB
120 ºC, adjustable to 110 or 100 ºC
H Thermostat TR 95 ºC, adjustable to
100 or 110 ºC
H Electronic maximum limit
Setting range: 20 to 127 ºC
Changes via coding address "06".
Control sequence
Boiler goes cold
(set value 2 K)
The burner start signal is set at the
set boiler water temperature less 2 K,
and the burner starts its own
monitoring program.
The burner start may be delayed by a
few minutes subject to the number
of the auxiliary circuits and the
combustion type.
Function description
(cont.)
Lower control range limit
In standard mode and when frost
protection is active, the control unit
regulates the boiler water
temperature subject to the
respective boiler.
Boiler heats up
The burner shutdown point is
determined by the shutdown
differential (coding address "13").
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