Viessmann vitotronic 300-k Operating Instructions Manual page 34

Additional Information
Terminology
(continued)
For outdoor temperature 7°F (−14°C):
A Underfloor heating system, slope 0.2 to 0.8
B Low temperature heating system, slope 0.8 to 1.6
C Heating system with a boiler water temperature in
excess of 167°F (75°C), slope 1.6 to 2.0
Factory settings: Slope = 1.4 and shift = 0.
Outdoor temperature
Legend
A Changing the slope:
The gradient of the heating curves changes.
B Changing the shift:
The heating curves are shifted in parallel in a vertical
direction.
C Changing the standard room temperature (set value):
The heating curves are offset along the "Set room
temperature" axis.
34
Heating curve
Heating curves illustrate the relationship between the
outdoor temperature, the set room temperature and the
boiler water temperature or supply temperature.
The lower the outdoor temperature, the higher the boiler
water temperature or supply temperature.
In order to guarantee sufficient heat and minimum fuel
consumption at any outdoor temperature, the conditions
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 with the following
settings:
H Heating curve shift = 0
H Standard room temperature (set value) = 68°F (20°C)
Heating circuit
A heating circuit is a sealed unvented circuit between the
boiler and radiators, in which the heating water circulates.
A heating system may comprise several heating circuits.
For example, one heating circuit for the rooms occupied
by you and one heating circuit for the rooms of a separate
apartment.
Heating circuit pump
Circulation pump for circulating the heating water in the
heating circuit
Mixer
Hot heating water from the boiler is mixed with cooled
heating water from the heating circuit. The heating water,
brought to the right temperature as required, is pumped
to the heating circuit by the heating circuit pump. The
control unit adjusts the supply temperature via the
mixer to suit different conditions, e.g. changing outdoor
temperatures.
Night setback
See "Reduced heating mode"
Room air dependant operation
The combustion air is drawn from the room where the
boiler is installed.
Direct vent operation
The combustion air is drawn from outside the building.
Room temperature
H Standard room temperature:
For periods when you will be at home during the day,
select the standard room temperature.
H Reduced room temperature:
For periods when you will be absent or during the night,
set the reduced room temperature; see "Heating mode".
Vitotronic 300-K Operating