Viessmann Vitocal 350-A Installation And Service Instructions Manual page 138

Troubleshooting
Control unit diagnostics
Message
System characteristics Cause
«5A DHW sensor bottom
Operation with tempera-
ture value of the upper
cylinder temperature
sensor. DHW heating is
blocked if only one sen-
sor is available or both
sensors are faulty.
«5C DHW solar
«60 Buffer cylinder sensor
Buffer cylinder is heated
once every hour. Heating
stops according to set
value of the return tem-
perature sensor.
«63 Ext. heat source
External heat source is
blocked. Instantaneous
heating water heater (if
installed) is enabled.
«68 Buffer cylinder sensor
Buffer cylinder is heated
once every hour. Heating
stops according to set
value of the return tem-
perature sensor.
«6B Ext. heat source
External heat source is
blocked. Instantaneous
heating water heater (if
installed) is enabled.
138
(cont.)
Break, bottom cylinder
temperature sensor
Break, Vitosolic cylinder
temperature sensor
Short circuit, buffer cylin-
der temperature sensor
Short circuit, external
heat source temperature
sensor
Break, buffer cylinder
temperature sensor
Break, external heat
source temperature sen-
sor
Measures
Check resistance (Pt 500)
at connections 3X1.13
and 3X2.13; replace sen-
sor if required.
Check sensor and replace
if required (see Vitosolic
installation and service
instructions).
Check resistance (Pt 500)
at connections 3X1.22
and 3X2.22; replace sen-
sor if required.
Check resistance (Pt 500)
at connections 3X1.4 and
3X2.4; replace sensor if
required.
Check resistance (Pt 500)
at connections 3X1.22
and 3X2.22; replace sen-
sor if required.
Check resistance (Pt 500)
at connections 3X1.4 and
3X2.4; replace sensor if
required.