Viessmann Vitocal 350-A Installation And Service Instructions Manual page 222

Connection and wiring diagrams
Safety chain, control circuit, main power...
P Mixer ~CLOSED, heating circuit
with mixer M2
R Heating circuit pump for heating cir-
cuit with mixer M2
S Cylinder primary pump / shut-off
valve
T Control of immersion heater EHE
or
DHW reheating with circulation
pump from external heat source
222
(cont.)
U Fan motor
Z For continuation of control circuit,
see previous illustration
sG Secondary pump (plug in cable har-
ness)
Colour coding to DIN IEC 60757:
BU Blue
RD Red
YE Yellow