Viessmann VITOTRONIC 100 Installation And Service Instructions Manual page 76

Installation
External hook−up in multi−boiler systems without LON
Starting burner stage 1 and 2
Contact closed:
Both burner stages are switched ON.
The boiler water temperature is
limited by the electronic maximum
temperature limiter, if it is set below
that of mechanical control
thermostat "R".
Burner stage 2 is shut down 2 K
sooner.
Contact opened:
Burner stages 1 and 2 are shut down.
76
Enable boiler, butterfly valve
Contact closed:
H Vitocrossal 300:
The butterfly valve opens.
H Low temperature boiler:
Initially, the pre−heat function for
lag boilers is activated. After the
pre−heat function has expired, the
minimum boiler water temperature
will be maintained, and the burner
stages can be controlled externally.
The butterfly valve opens.
Contact opened:
The butterfly valve is closed after
approx. 5 min.
Burner stages cannot be switched
ON externally; a minimum
temperature will not be maintained.
(cont.)