Viessmann VITOTRONIC 100 Installation And Service Instructions Manual page 72

Installation
External hook−up in single boiler systems
Control unit settings
Code "01: 1"
(delivered condition)
Code "02: 1"
(delivered condition)
The boiler water temperature must
be set to the lower value. The boiler
is held at the required minimum
temperature.
The high limit safety cut−out settings
and other settings are subject to the
system equipment and the safety
equipment in accordance with
DIN 4751 2.
72
(cont.)
Starting burner stage 1
Contact closed:
Burner stage 1 is started. To maintain
the minimum temperature, the
burner is switched to full load via
Vitotronic 100. An external
modulation controller regulates the
load−dependent modulation.
The boiler water temperature is
limited by the electronic maximum
temperature limiter, if it is set below
that of mechanical control
thermostat "R".
Contact opened:
Burner stage 1 is shut down.