Viessmann VITOCAL 300 Installation And Service Instructions Manual page 131

Terminals inside the control panel (230 V∼)
Terminal des- Function
ignation
15 Instantaneous heating water heater stage 1 (3 kW)
(contactor control)
16 Mixer 1 OPEN
(primary cooling circuit or external heat source)
17 Mixer 1 CLOSE
(primary cooling circuit or external heat source)
18 Heating circuit pump (direct heating circuit)
19 Cylinder primary pump
20 Immersion heater for DHW cylinder
(contactor control)
21 Instantaneous heating water heater stage 2 (6 kW)
22 not used
23 Mixer 2 OPEN (heating circuit with mixer)
24 Mixer 2 CLOSE (heating circuit with mixer)
25 Circulation pump, heating circuit with mixer
—
26
27 DHW circulation pump
28 Central fault message, zero volt
29 Central fault message, zero volt
30 Natural cooling extension kit control
31 Actuation of external heat source
32 Three-way diverter valve, heating/DHW OPEN
33 Three-way diverter valve, heating/DHW CLOSE
K10 Compressor
K20 Instantaneous heating water heater stage 1 (3 kW)
K30 Instantaneous heating water heater stage 2 (6 kW)
(contactor control)
K32 Primary pump/intermediate circuit pump (type WWC)
Connection and wiring diagrams
(cont.)
131