Viessmann VITOCAL 300 Installation And Service Instructions Manual page 138

Connection and wiring diagrams
Control PCB
(cont.)
A Connection to the control PCB,
sensors and remote controls (see
page 133, X13 to X4 and X4 to
X3)
B Power supply from main isolator
and phase monitor
C Safety chain input (individual free
core from X8.1, see page 135)
D On-site contactor for primary
pump in systems with intermedi-
ate circuit
8 Control PCB
wI External heat pump control
eU Natural cooling control
eI Mixer 1, external heat source or
primary cooling circuit OPEN
eO Mixer 1, external heat source or
primary cooling circuit CLOSE
rP Heating circuit pump, direct heat-
ing circuit
rP Heating circuit pump, direct heat-
ing circuit
rQ Cylinder primary pump
rW Immersion heater, DHW cylinder
138
rE Instantaneous heating water hea-
ter stage 2 (6 kW)
rR Mixer 2 OPEN (heating circuit with
mixer)
rT Mixer 2 CLOSE (heating circuit
with mixer)
rZ Heating circuit pump heating cir-
cuit with mixer
rI DHW circulation pump
rO Central fault message, zero volt
tP Central fault message, zero volt
tQ Electric heater stage 1 (3 kW)
tW Secondary pump (integral)
tE Primary pump or intermediate cir-
cuit pump for type WWC (integral)
tT Solenoid valve, LPG, compressor
tZ Compressor
tU Instantaneous heating water hea-
ter stage 2 (6 kW)
tI On-site contactor for primary
pump in systems with type WWC
with intermediate circuit.
The control pulse can be taken
from the coil connection of K32.