Viessmann VITOTRONIC 100 GC1B Installation And Service Instructions Manual page 94

Function Description
Boiler Water Temperature Control
Multi Boiler System
Plug sÖA1 of the Vitotronic is used as switching
contact.
Required code: "0d:1" in category 2 "Boiler" and
"4C:2" in category 1 "General"
Legend
sÖA1 Closing the mixing valves
Contactor relay connection to boiler #1
A1
Contactor relay connection to boiler #2
A2
B Downstream heating circuit controller, switching
contact closed:
Signal for mixing valve "Close"
C Power supply, 120V/60 Hz
D Junction box, on site
Legend
sÖA1 Closing the mixing valves
Contactor relay connection to boiler #1
A1
Contactor relay connection to boiler #2
A2
B Downstream heating circuit controller, switching
contact closed:
Signal for mixing valve "Close"
C Power supply, 120V/60 Hz
Junction box, on site
D
94
Vitotronic 100, GC1B Installation and Service
(continued)
Distribution Pump
For heating systems with remote substation (> 20 m).
Requirement:
The heat transfer must be able to be reduced.
Also affects the heating circuits.
The distribution pump must be started by a higher third
party control unit if a boiler is enabled.
Size the distribution pump to approx. 110% of the total
throughput.
With injection control:
For heating circuits that require heat immediately a heat
demand is issued (e.g. air heaters).
Function
Multi boiler systems with distribution pump and low
pressure distributor
Temperature sensor T1 records the return temperature.
The burner is ramped up to full load if the factory-
selected set temperature (defaulted by the boiler coding
card) is not being achieved. The flow rate is reduced
via the mixing valve. The mixing valves are fully closed
upon demand.
When the set temperature is exceeded, the mixing
valves are opened and the flow rate gradually increased
to 100%.
Multi boiler systems with distribution pump and injection
control
Temperature sensor T1 records the return temperature.
The burner is ramped up to full load if the factory-
selected set temperature (defaulted by the boiler coding
card) is not being achieved. The flow rate is reduced
via the mixing valve. For this, the mixing valves are
proportionally or fully closed.
When the set temperature is exceeded, the mixing
valves are opened and the flow rate gradually increased
to 100%.
Connection in Heating Systems Without LON
Multi Boiler System
Plug sÖA1 of the Vitotronic is used as switching
contact.
Required code: "0d:1" in category 2 "Boiler"
and "4C:2" in category 1 "General"