Viessmann Vitocal 300-G Installation And Service Instructions Manual page 130

Troubleshooting
Control unit diagnostics
ID Message
(priority)
D4 Control high
pressure ("i")
D6 Flow switch
("U")
E1 Ext. Heat gen-
eration ("U")
E2 Fault, lag heat
pump ("U")
FF New start ("i")
Heat pump characteristics in case of messages
All messages have a 2-digit number as identifier, the so-called "ID". This num-
ber corresponds to the ID in the table above "Message display" from page 120.
ID Characteristics and effects of system/control unit
10 Outside temperature is assumed to be -40 °C.
18
20 The temperature value of the secondary return sensor plus 5 K is se-
28 lected. The heat pump is stopped (message A9) if the secondary flow
and return temperature sensors are faulty.
21 The temperature value of the secondary flow sensor plus 5 K is se-
29 lected. The heat pump is stopped (message A9) if the secondary flow
and return temperature sensors are faulty.
130
(cont.)
1. Cause
2. Measures
1. Air in the heating circuit; secondary
or heating circuit pump blocked; con-
denser contaminated; pressure sen-
sor faulty
2. Vent heating circuit; check second-
ary and heating circuit pump; flush
heating circuit; check system pres-
sure
1. The flow switch has responded;
inadequate throughput
2. Check primary pumps and circula-
tion pump for brine/primary circuit.
For type WW/WWC check filter and
intermediate circuit heat exchanger;
check primary circuit pressure
1. Fault on the external heat source
2. Check external heat source
1. Fault at the lag heat pump in a cas-
cade
2. Check the lag heat pump display
1. Control unit restart
2. No measures required
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