Adding External Boiler As Last In Boiler Sequence - Viessmann VITOTRONIC 300 Installation And Service Instructions Manual

External functions
(cont.)
Function External blocking boiler
Contact
Closed
■ ■
■
Note
If all boilers are blocked or no other boiler
is ready for operation, the heating system
is not protected against frost.
Open The boiler is enabled.
■
Parameter
—

Adding external boiler as last in boiler sequence

!
Please note
Live contacts lead to short circuits or phase fail-
ure.
The external connection must be potential-
free.
Function Start the boiler externally as the last one in the boiler sequence
Control unit
■
■
Connection Plug
1
143
B
A
B
Contact
Closed This boiler is started last if the other boilers in the heating system cannot provide suffi-
■
cient heat.
Open The boiler is integrated into the current boiler sequence.
■
Boiler is blocked.
Shut-off devices are closed.
The boiler circuit pump or shunt pump (if
installed) is switched off.
Vitotronic 300 (for assigned boilers)
Vitotronic 100
.2/ .3
aVD aVD
A
2 3
Floating contact
Plug of the control unit
aVD
Electrical connections
External system blocking
All boilers are blocked.
Shut-off devices are closed.
Note
There is no frost protection for the heating
system.
All boilers are enabled.
Set "42" (DE1), "43" (DE2) or "44" (DE3) in
the "General" group to 3 or 4.
33