Function Description Boiler Water Temperature Control - Viessmann VITOTRONIC 100 Installation And Service Instructions Manual

Function description
Boiler water temperature control
Brief description
The boiler water temperature is
regulated by starting up and shut-
ting down the burner.
In the delivered condition, the
switching differential is ±2 K, rela-
tive to the current set value.
When the DHW cylinder is being
heated up, a set boiler water tem-
perature is defaulted that lies 20 K
above the set DHW cylinder tem-
perature (adjustable via coding
address 60).
Functions
The boiler water temperature is
recorded by three separate sensors
that are inserted into a multiple sensor
well:
High limit safety cut-out (STB)
(liquid expansion)
TR control thermostat (liquid expan-
sion)
KTS boiler water temperature sen-
sor (change in resistance PT 500)
Upper control range limits:
High limit safety cut-out STB 110/
100/95 ºC
Control thermostat TR 75/87/95 ºC
Electronic maximum limit:
Setting range: 20 ºC to 130 ºC
Changes via coding address 06
This limit is only effective within
the control range (not for DHW
cylinder heating)
32
The boiler water temperature is lim-
ited by the control thermostat.
Coding addresses that influence
the regulation of the boiler water
temperature:
00 to 04, 06, 10 to 12, 28.
For a description, see the coding
overview.
Lower control range limits:
Ultra low temperature boiler:
At an outside temperature of 1 °C,
the boiler water temperature will be
regulated to at least 15/22 °C (frost
protection).
Low temperature boiler to 69 kW:
In standard operation and with
active frost protection, the boiler
water temperature will be regulated
to 35/42 ºC.
Auxiliary circuits:
Two-stage burner:
An extension can be connected for
controlling a two-stage burner.
Plug X12 for external burner start
(see page 15).