External Burner Blocking 150; Connections To Terminal Aba - Viessmann VITOTRONIC300 Installation And Service Instructions Manual

Installation Sequence
External Burner Blocking
Legend
A Dry contact
B DIN rail

Connections to Terminal aBA

Legend
A Dry contact
B DIN rail
44
150
B
B
A
Vitotronic 300, GW2B Installation and Service
Note: 'Live' contacts lead to short circuits or phase
failure. The external connection must be floating.
Remove jumper from DIN terminals 16 and 17.
Note: Connect only safety shutdown equipment (dry
contact), e.g. a combustion air device adaptor, to
these terminals.
Opening this contact leads to a burner control shutdown.
Note: The heating system has no frost protection during
blocking. The boiler is not held at the lower boiler
water temperature.
External shut-off
1. Remove jumper between terminals 19 and 20.
2. Connect dry contact. Controlled switch-off takes place
when the contact is opened.
WARNING
The terminals should be used for safety switch-off
purposes only (e.g. through a high limit thermostat).
During switch-off, there is no frost protection of the
heating system and the boiler is not kept at the minimum
boiler water temperature.