"External Hook-Up" Is Displayed; "External Program" Is Displayed - Viessmann VITOTRONIC 300 Operating Instructions Manual

and "Service" are displayed
ë
Cause
The time for a service as specified by your contractor
has arrived.

"External hook-up" is displayed

Cause
The operating program set at the control unit was e.g.
changed over via an externally connected button.
Example: In a school, heating demand exists outside of
school times, e.g. for a parents' evening.

"External program" is displayed

Cause
The operating program set at the control unit has been
changed by another control device.
Remedy
Proceed as described on page 37.
Remedy
No action required. This function cannot be influenced
via the control unit. Once the external changeover no
longer applies, the set operating program becomes ac-
tive again.
Remedy
You can change the operating program.
What to do if...
47