Viessmann VITODENS 343-F WS4A Installation And Service Instructions Manual page 132

Designs
Connection and wiring diagram
A3 Optolink
A4 Burner control unit
A5 Programming unit
A6 Coding card
A8 LON communication module
A9 Internal extension H1
S1 ON/OFF switch
S2 Reset button
X ... Electrical interface
% Cylinder temperature sensor
sÖ Circulation pump 230 V
sA Cylinder primary pump 230V
132
internal . . .
(cont.)
dG Gas solenoid valve
fÖ Mains input 230V/50Hz
gD External safety valve (if
installed)
lH Power supply, internal extension
H1
a-Ö Fan motor
aYA Gas pressure limiter (accessory)
aVG KM BUS
a:Ö Modulation coil
A To the wiring chamber (see the
following page)