Brief Description; Auxiliary Circuits - Viessmann Vitotronic 100 Installation And Service Instructions Manual

Function description
Boiler water temperature control

Brief description

The boiler water temperature is regulated by switch-
■
ing the burner on or off. In the delivered condition,
the switching differential is
rent set value.
■ The set boiler water temperature is determined from
the following parameters:
Heating circuit set flow temperature
–
Set DHW temperature
–
– External demand
Functions
The boiler water temperature is captured by the follow-
ing equipment:
■ High limit safety cut-out STB (liquid expansion)
Temperature controller TR (liquid expansion)
■
Boiler water temperature sensor NTC 10 k
■
Upper control range limits:
■ High limit safety cut-out STB 110/100/95 °C
■ Temperature controller TR 75/87/95 °C
Electronic maximum temperature limit:
■
Setting range: 20 to 127 °C
–
Changed via coding address "06" in group 2
–
"Boiler".
The limit is only effective within the control range
(not for DHW cylinder heating).
Lower control range limits:
Boiler water temperature regulated subject to the rele-
vant boiler (specified by the coding card).
Operation with Vitotrol 100
For connection, see page 15 and separate installation
instructions.
Set code "40:0" in group 1 "General".
During the heating times enabled by the Vitotrol 100, in
the "Heating and DHW" operating program, when
there is demand, heating is carried out to the set boiler
water temperature selected at the control unit. The
boiler is maintained at the minimum temperature speci-
fied by the coding card.
Effect on the heating circuit pump in the "Heating
and DHW" operating program
The heating circuit pump is switched ON if the contact
is closed. Cylinder priority is observed.
When there is no longer any heat demand, the contact
is opened and the heating circuit pump remains on for
the selected run-on time (coding address "F5" in group
5 "Heating circuit").
62
2 K, relative to the cur-
±
Ω
If a Vitotrol 100 is connected, it is only switched on if
■
required by the Vitotrol 100.
■ When the DHW cylinder is heated, the specified set
boiler water temperature is 20 K above the set DHW
temperature (adjustable via coding address "60" in
group 3 "DHW").
System protection
In the "DHW only" and "Standby mode" operating pro-
grams, the heating circuit pump can be started in order
to protect the system (coding addresses "F6" and "F7"
in group 5 "Heating circuit"). There is no set value
demand while the pump is running.
Note
When there is demand from the DHW cylinder, the
heating circuit pump is switched off. When cylinder
heating is complete, the heating circuit pump starts
cycling again.

Auxiliary circuits

Extension for controlling a 2-stage burner (see
■
page 22).
External hook-ups (messages) via external EA1
■
extension (see page 65).
■ Plug "X12" for external burner start (see page 19).
■ Plug for external demand or external blocking
lH
(see page 20 or 21).
Burner switching hysteresis
Permanent switching hysteresis
Code "04:0"
ON
OFF
+2
set
-2
low average
heat demand heat demand
Fig. 35
Heat demand-dependent switching hysteresis
The heat demand-dependent switching hysteresis
takes the boiler utilisation level into account.
Time
high
heat demand