Setting heating programs
The heating system frost protection (see frost protection function)
applies to all heating programs.
You can select the following operating programs with the program
keys:
■ Heating and DHW
■ Only DHW
■ Standby mode
Optional external changeover of heating program for all heating cir-
cuits together or for selected heating circuits only.
Frost protection
■ The frost protection function is switched on if the temperature drops
approx. +1 °C below the outside temperature, i.e. the heating circuit
pump is switched on and the boiler water is maintained at a lower
temperature (see chapter "Operating conditions with Vitotronic boiler
control units").
■ "Standby mode":
The frost protection function is switched off if the outside temperature
is exceeded by approx.+3 °C, i.e. the heating circuit pump and
burner are switched off.
■ "Heating and DHW"
The frost protection function is switched off if the outside temperature
is exceeded by approx. +3 °C, i.e. the heating circuit pump is
switched off and the low-end boiler water temperature required for
the relevant boiler is maintained as necessary (see chapter "Oper-
ating conditions with Vitotronic boiler control units").
Summer mode
("DHW only")
The burner starts only when the DHW cylinder needs reheating (con-
trolled by the cylinder thermostat).
The respective low-end boiler water temperature of each boiler is
maintained if necessary.
Adjusting the heating curves (slope and level)
The Vitotronic 300 controls the boiler water temperature (=system flow
temperature) and the flow temperature of the heating circuits with
mixer in weather-compensated mode. The boiler water temperature is
automatically boosted by between 0 and 40 K above the currently
required set flow temperature (delivered condition 8 K).
The flow temperature required to reach a specific room temperature
depends on the heating system and the thermal insulation of the build-
ing to be heated.
Adjusting both heating curves matches the boiler water temperature
(= system flow temperature) and the flow temperature to these oper-
ating conditions.
The upper boiler water temperature is limited by the thermostat and
the electronic maximum temperature limiter.
Specification
Rated voltage 230 V~
Rated frequency 50 Hz
Rated current 2 x 6 A
Power consumption 10 W
Protection class I
IP rating IP 20 D to EN 60529;
ensure through appro-
priate design/installa-
tion
Function Type 1B to
EN 60 730-1
Permissible ambient temperature
– during operation 0 to +40 °C
Installation in living
spaces or boiler rooms
(standard ambient con-
ditions)
– during storage and transport -20 to +65 °C
Rated capacity of the relay outputs
sÖ
Heating circuit pumps
or
Primary pump, primary store system
or
Circulation pump - flue gas/water
heat exchanger, if installed
or
Switching output 4(2) A, 230 V~
sA
Circulation pump for cylinder heat-
ing
4(2) A, 230 V~
sK
DHW circulation pump 4(2) A, 230 V~
sL
Shunt pump 4(2) A, 230 V~
gÖ
Central fault message 4(2) A, 230 V~
gS
Mixer motor
or
Mixer motor constant return temper-
ature control
or
Motor, 3-way mixing valve, primary
store system 0.2(0.1) A, 230 V~
Total sÖ, sA, sK, sL, gÖ, gS
max. 6 A, 230 V~
fA Burner 4(2) A, 230 V~
lÖ Burner, two-stage, if installed 1(0.5) A, 230 V~
lÖ Burner, modulating, if installed 0.2(0.1) A, 230 V~
Control units
(cont.)
OIL/GAS BOILERS
VIESMANN
59
5822 426 GB
11