External Hook−Up In Multi−Boiler Systems Without Lon - Viessmann VITOTRONIC 100 Installation And Service Instructions Manual

External hook−up in multi−boiler systems without LON
Operation with a two−stage burner
Zero volt contacts of the higher
control unit:
Burner stage 1 ON
Burner stage 2 ON
Enable boiler, open
or close the butterfly
valve
143 146
Adjustments on every control unit
Set code "01: 3".
The high limit safety cut−out settings and other settings are subject to the
system equipment and the safety equipment in accordance with DIN 4751 2.
Starting burner stage 1
Contact closed:
Burner stage 1 is started. Burner
stage 2 is switched ON only for
maintaining the minimum
temperature (only for low
temperature boilers).
The boiler water temperature is
The connections on plug aVD and
aVH are required when connecting
an external hook−up. The DHW
cylinder temperature and the
load−dependent cascade control
must be regulated by an external
control unit.
!
Please note
The contact "Boiler enable"
must be provided in
multi−boiler systems to prevent
boiler damage. This contact
must always be closed on the
lead boiler.
limited by the electronic maximum
temperature limiter, if it is set below
that of mechanical control
thermostat "R".
Contact opened:
Burner stage 1 is shut down.
Installation
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