Ad Mixer Heating/Dhw - Viessmann VITOTRONIC 200 Service Instructions Manual

Troubleshooting
Message overview

AD Mixer heating/DHW

No changeover between heating mode and DHW heat-
ing.
Cause
3-way diverter valve "Heating/DHW heating" is faulty.
AE Cyl sensor top/bottom
Cause
Top and bottom temperature sensors interchanged in
the DHW cylinder.
AF Cylinder primary pump
Inadequate change of temperature in the DHW cylin-
der
Cause
Circulation pump for cylinder heating faulty
■
Cylinder loading system flow rate too low; cylinder
■
loading pump or 2-way valve on cylinder loading sys-
tem faulty
B0 Device recognition
■ Heat pumps with refrigerant circuit controller [7-1]:
Heat pump starts. Refrigerant circuit runs with
reduced efficiency.
Other heat pumps: The heat pump does not start.
■
94
(cont.)
Measure
Check function of 3-way diverter valve (see "Function
check")
Check voltage at terminal 211.4 (see "main PCB"); re-
place 3-way diverter valve if necessary.
Measure
No action required. Heat pump control unit interchang-
es the sensors internally.
Measure
Measure the voltage at the following connections:
Vitocal 300-A:
■
Connection 224.6, see "Expansion PCB".
Other heat pumps:
■
Connection 211.4, see "Main PCB".
Check circulation pumps and 2-way valve are mechani-
cally sound. If necessary replace circulation pumps
and/or 2-way valve.