Viessmann Vitotronic 100 GC1 Installation And Service Instructions Manual page 26

Heating system designs
System version 7
(cont.)
Vitotronic 300-K, MW1S
Required coding
00: 3, Without system circuit A1
00: 4,
00: 7,
or
00: 8
Vitotronic 300-K, MW1S with
35: 1 one Vitotronic 100, GC1
35: 2 two Vitotronic 100, GC1
35: 3 three Vitotronic 100, GC1
39: 1 Setting up Vitocrossal 300 as permanent lead boiler
to
39: 4
3b: 3 Autonomous series connection with supply temperature sensor
*1
If required.
Possible applications
For heating circuits with temperature differentials ≥20 °C / 68 °F
The Vitocrossal 300 (lead boiler) and the next Vitorond (lag boiler) are operated via a Viessmann control system with
outdoor reset logic, modulating boiler water temperature, and load-dependent sequential control – two-stage or modulating
burners are controlled.
Vitocrossal 300 is equipped with two return connections. The heating circuits with the higher return temperature are
connected to the upper return connection, and those with lower return temperatures to the lower return connection.
Please note: Connect at least 15% of the rated output to the lower return connection.
Temperature sensor T1 senses the return temperature.
The boiler control unit regulates the three-way mixing valve to ensure that the system never falls below the minimum
return temperature.
Due to the LON-BUS communication between controls, a boiler supply temperature is automatically set.
This temperature is based on the highest required mixing valve circuit temperature plus adjustable differential.
IMPORTANT
The connection diagram is only a recommendation and needs to be verified for completeness and functionality at the
installation site. Single-phase and three-phase pumps must be connected with field supplied motor contactors and/or
motor starters.
26
*1