Technical data

123
Function description – Vitotronic 100
Boiler temperature control
Brief description
The boiler water temperature is
regulated by controlling a two stage or
modulating burner.
The set boiler water temperature
set-point is controlled by Vitocontrol-S,
VD2/CT3/CM2.
Coding addresses which influence the
boiler temperature control
02 to 06, 08 to 0b, 13 to 1C.
For a description, see the coding
overview.
Functions
The boiler water temperature is
monitored by three sensors separately,
which are inserted into a multiple
sensor well:
Fixed high limit (FHL) (liquid
expansion)
Adjustable high limit (AHL)
(liquid expansion)
Boiler temperature sensor KTS
(changes in resistance PT500)
Control range limits top:
 Fixed high limit (FHL) 110˚C /
230˚F, adjustable to 99˚C / 210˚F
 Thermostat (AHL) 95˚C / 203˚F,
adjustable to 87 or 100˚C / 187 or
212˚F.
 Electronic maximum limiter
setting range: 20 to 127˚C / 68 to
261˚F
The maximum boiler water
temperature limit can be adjusted via
coding address 06.
Lower control range limits
In standard mode and when frost
protection is active, the control unit
regulates the boiler water temperature
in accordance with the respective
boiler.
Control sequence
Boiler goes cold
(set value –2 K)
The burner is activated if the boiler
temperature is 2˚C / 3.6˚F below the
calculated set point temperature.
The burner may be delayed a few
minutes depending on the connected
auxilliary equipment and the fuel type.
Boiler heats up
The burner shutdown point is
determined by the switch-off
differential (coding address 13).
5351 340 v1.4