Viessmann VITODENS 300 Service Instructions Manual page 108

Designs
Connection and wiring diagrams
A3 Optolink
A4 Burner control unit
A5 Programming unit
A6 Coding card
A7 Connection adaptor
A8 LON communication module
S1 ON/OFF switch
S2 Reset button
! Outside temperature sensor
? Flow temperature sensor, low
loss header
108
external . . .
(cont.)
% Cylinder temperature sensor
(plug on the cable harness)
sÖ Internal circulation pump
dG Gas solenoid valve
fÖ Power supply
lH Power supply accessories and
Vitotrol 100
a-Ö Fan motor
aYA Gas governor
aVG KM BUS