Viessmann VITOCAL 300-G Installation And Service Instructions Manual page 131

Messages
(cont.)
Message
System characteristics Cause
31 Return sensor primary
Operation with tempera-
ture value of flow temper-
ature sensor in primary
circuit, minus 2 K. If both
temperature sensors
(primary flow and return)
are faulty, the heat pump
stops (message A9)
38 Flow sensor primary
Operation with tempera-
ture value of return tem-
perature sensor in pri-
mary circuit, plus 3 K. If
both temperature sen-
sors (primary flow and
return) are faulty, the
heat pump stops (mes-
sage A9)
39 Return sensor primary
Operation with tempera-
ture value of flow temper-
ature sensor in primary
circuit, minus 2 K. If both
temperature sensors
(primary flow and return)
are faulty, the heat pump
stops (message A9)
40 Flow sensor HC2
Mixer heating circuit M2
is closed
41 Flow sensor HC3
Mixer heating circuit M3
is closed
Short circuit, primary cir-
cuit temperature sensor,
brine outlet
Lead break, flow temper-
ature sensor, primary
(heat pump brine inlet)
Lead break, primary
return temperature sen-
sor (brine outlet)
Short circuit, flow tem-
perature sensor in heat-
ing circuit with mixer M2
Short circuit, flow tem-
perature sensor in heat-
ing circuit with mixer M3
Troubleshooting
Measures
Check resistance (Pt 500)
at plug-in connection F3
and terminals X5.4/X5.5;
replace sensor if
required.
Check resistance (Pt 500)
at plug-in connection F2
and terminals X5.2/X5.3;
replace sensor if
required.
Check resistance (Pt 500)
at plug-in connection F3
and terminals X5.4/X5.5;
replace sensor if
required.
Check resistance (Ni 500)
at plug-in connection F12;
replace sensor if
required.
Check sensor and replace
if necessary (see installa-
tion instructions for exten-
sion kit for heating circuit
with mixer).
131