Viessmann VITOTRONIC 300 Operating Instructions Manual page 52

Appendix
Terminology
(cont.)
Open source licences
The programming unit firmware contains open source
software components. Such software is released under
an open source licence and thus available to every-
one.
The full text of the licence can be displayed using the
menu point of the same name.
Reduced heating mode
For periods when you will be absent or during the
night, heat your rooms to the reduced room tempera-
ture. Set the periods using the time program for central
heating. With underfloor heating systems, reduced
heating mode only yields limited energy savings (see
"Underfloor heating system").
Room temperature-dependent heating mode
In room temperature-dependent mode, the flow tem-
perature is controlled according to the room tempera-
ture. More heat is made available at a lower room tem-
perature than at a higher one.
The room temperature is captured and transmitted to
the control unit by a sensor. The sensor is fitted in the
room.
The flow temperature is regulated independently of the
outside temperature.
110
100
90
80
70
60
50
40
30
Fig. 45
Example:
For outside temperature
Underfloor heating system, slope 0.2 to 0.8
A
Low temperature heating system, slope 0.8 to 1.6
B
Heating system with a boiler water temperature in
C
excess of 75 °C, slope 1.6 to 2.0
52
10 5 0 -5 -10 -15 -20
Outside temperature in °C
14 °C:
−
Weather-compensated heating mode
In weather-compensated mode, the flow temperature
is controlled according to the outside temperature.
More heat is made available at a lower outside temper-
ature than at a higher one.
The outside temperature is captured and transmitted to
the control unit by a sensor. The sensor is fitted to the
exterior of the building.
Heating curve
Heating curves illustrate the relationship between the
outside temperature, the set room temperature and the
boiler water temperature or flow temperature. The
lower the outside temperature, the higher the boiler
water temperature or flow temperature.
In order to guarantee sufficient heat and minimum fuel
consumption at any outside temperature, the condi-
tions of your building and your heating system must be
taken into consideration. The heating curve is set by
your heating contractor for this purpose.
The illustrated heating curves apply under the follow-
ing settings:
Heating curve level = 0
■
■ Standard room temperature (set value) = 20 °C
Slope
1.8
1.6
C
1.4
1.2
1.0
B
0.8
0.6
0.4
A
0.2
-25 -30