Viessmann VITOTRONIC 100 GC1B Installation And Service Instructions Manual page 92

Function Description
Boiler Water Temperature Control
Legend
sÖA1 Closing the mixing valves
A Contactor relay
Downstream heating circuit controller, switching
B
contact closed:
Signal for mixing valve "Close"
Legend
sÖA1 Closing the mixing valves
Contactor relay connection to boiler #1
A 1
Contactor relay connection to boiler #2
A2
Downstream heating circuit controller, switching
B
contact closed:
Signal for mixing valve "Close"
Power supply, 120V/60 Hz
C
D Junction box, on site
92
Vitotronic 100, GC1B Installation and Service
(continued)
Connection in Heating Systems Without LON
Single Boiler System
Plug sÖA1 of the Vitotronic is used as switching
contact for the Therm-Control.
Required code: "4C:2" in category 1
"General"
Multi Boiler System
Plug sÖA1 of the Vitotronic is used as switching
contact for the Therm-Control.
Required code: "0d:1" in category 2 "Boiler"
and "4C:2" in category 1 "General"
Raising the Return Temperature Via Shunt Pump or/and
3-way Mixing Valve
With shunt pump:
For heating systems with distributor installed close
to the boiler.
With 3-way mixing valve:
For heating systems where downstream heating circuits
cannot be controlled, e.g. older heating systems
or commercial green houses.