Viessmann Vitocal 300-G Series Installation And Service Instructions Manual page 26

Installation sequence
Electrical connection
High limit safety cut-out for heat pump in conjunc-
tion with an external heat source
X3.1
B
222.3
A
222.4
D
K1
X2.N
Fig. 16
Terminals on extension PCB
A
Move jumper from X3.1 to 222.3
B
C Connection on the external heat source at termi-
nals for external demand
High limit safety cut-out (max. 70
D
protection
K1 Relay; sizing in accordance with the external heat
source; observe safety instructions
Plug
sXD
Terminals Function
223.1 Central fault message
223.2
U
Central fault message
223.1
230V~, 0.5 A
A
223.2
Fig. 17
A Terminals on extension PCB
26
(cont.)
C
C) as heat pump
º
L1
N
Explanation
Floating contact:
Closed: Fault
■
Open: No fault
■
Not suitable for safety LV
■
Connection values (contact rating):
Voltage: 230 V~
■
Max. switching current: 4(2) A
■