Connection To Low Water Cut-Off Device; Connection To Terminal 151 - Viessmann Vitotronic 300 Installation And Service Instructions Manual

Installation Sequence
Connection of Low Water Cut-off Device
A
Legend
aBH Power supply for accessories.
aBÖ Connection for external equipment.
A Low water cut-off (typical)
Connections to Safety Equipment
Connections to Terminal aBA
Legend
A External shut-off (dry contact)
B DIN rail
20
Vitotronic 300, GW5B Installation and Service
1. Remove jumper between terminals 12 and 15.
2. Make connection as shown in diagram.
CAUTION
The diagram shown is only a simplified conceptual
drawing of a typical low water cut off (LWCO) device.
Refer to the manual specific to the device for
interconnection details.
1. Connect the external safety equipment in series.
Legend
A DIN rail
B Low water cutoff
C Other safety controls
External shut-off
1. Remove jumper (not shown) 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.
Note: The heating system has no frost protection while it
is blocked. The boiler is not held at the lower boiler
water temperature.