Viessmann VITOCAL 300-G Installation And Service Instructions Manual page 96

Installation sequence
Electrical connections
!
Please note
Protect the heat pump against
temperatures over 70 °C from the
external heat source.
Install high limit safety cut-out
(STB) or, if required, also take
additional measures (e.g. second
STB to switch off the secondary
pump).
Note
■ The switching contact to demand heat
from an external heat source in the
heat pump is a zero volt N/O contact
that closes in case of heat demand.
■ This contact can be subjected to a load
of 230 V~/4(2) A in case of an external
voltage supply. Never route low volt-
age via this contact; that requires an
on-site relay.
■ The boiler water temperature sensor in
the external heat source (plug F20)
must capture the average temperature
of the external heat source.
Appliance
Mixer motor, external heat
source
Control of an external heat
source
Circulation pump for DHW
reheating
96
(cont.)
222.3
222.4
D
A Terminals on main PCB with exten-
B Install jumper from X3.1 (cross con-
C Connection at the external heat
D High limit safety cut-out (this is set
K1 Relay; sizing in accordance with the
Connection
222.2V OPEN
X1.?
X2.N
222.1v CLOSE
222.3
222.4
224.7
X1.?
X2.N
X3.1
B
A
K1
X2.N
sion: Contact load 230 V~, 4(2) A,
zero volt contact
nect PCB) to 222.3 (main PCB with
extension)
source on the terminals for external
demand
to 70 °C) as heat pump protection
external heat source; observe
safety instructions
Required parameters:
Parameter Ó setting
"Ext. heat source"
■ "External heat source
7B00" Ó "1"
"Ext. heat source"
■ "External heat source
7B00" Ó "1"
"Ext. heat source"
■ "External heat source
7B00" Ó "1"
C