22
20 Flow sensor secondary
■
Operation with temperature value of return tempera-
ture sensor in secondary circuit, plus 5 K.
■
If the secondary circuit flow and return temperature
sensors are faulty at the same time, the message
"A9 Heat pump"
appears and the heat pump shuts
down.
Cause
Measure
Short circuit, secondary circuit flow temperature sensor Check resistance value (Pt500A) at plug F8 or at termi-
nals X25.9/X25.10: See "Controller and sensor PCB".
Replace sensor if required.
21 Return sensor secndry
■
Operation with temperature value of flow tempera-
ture sensor in secondary circuit, minus 5 K.
■
If the secondary circuit flow and return temperature
sensors are faulty at the same time, the heat pump is
switched off. After 24 h the message
"A9 heat
pump"
appears.
Cause
Measure
Short circuit, secondary circuit return temperature sen-
sor
Check resistance value (Pt500A) at terminals X25.11/
X25.12: See "Controller and sensor PCB". Replace
sensor if required.
28 Flow sensor secondary
■
Operation with temperature value of return tempera-
ture sensor in secondary circuit, plus 5 K.
■
If the secondary circuit flow and return temperature
sensors are faulty at the same time, the message
"A9 Heat pump"
appears and the heat pump shuts
down.
Cause
Measure
Lead break, secondary circuit flow temperature sensor
Check resistance value (Pt500A) at plug-in connection
F8 or at terminals X25.9/X25.10: See "Controller and
sensor PCB". Replace sensor if required.
29 Return sensor secndry
■
Operation with temperature value of flow tempera-
ture sensor in secondary circuit, minus 5 K.
■
If the secondary circuit flow and return temperature
sensors are faulty at the same time, the heat pump is
switched off. After 24 h the message
"A9 heat
pump"
appears.
Cause
Measure
Lead break, secondary circuit return temperature sen-
sor
Check resistance value (Pt500A) at terminals X25.11/
X25.12: See "Controller and sensor PCB". Replace
sensor if required.
Troubleshooting
Message overview
(cont.)
5800 917 GB
Maintenance