Viessmann VITOTRONIC 200 Service Instructions Manual page 40

Troubleshooting
Messages
(cont.)
Message
Code/system characteris-
tics
29 Return sensor secndry
Operation with tempera-
ture value of flow temper-
ature sensor in secon-
dary circuit minus 5 K. If
both temperature sen-
sors (secondary flow and
return) are faulty, the
heat pump is shut down
(message A9).
2A Return sensor sec. 2
Operation with tempera-
ture value of flow temper-
ature sensor in secon-
dary circuit minus 5 K. If
both temperature sen-
sors (secondary flow and
return) are faulty, the
heat pump is shut down
(message A9).
30 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 is shut down
(message A9).
40
Cause
Lead break, secondary
circuit return temperature
sensor.
Lead break, return tem-
perature sensor, secon-
dary circuit, heat pump
2nd stage (if installed).
Short circuit, flow tem-
perature sensor, primary
circuit (heat pump air
intake or brine inlet).
Measures
Check resistance (Pt 500)
at plug-in connection F9 or
terminals X5.10/X5.11
(see page 172); replace
sensor if required.
Check resistance (Pt 500)
at plug-in connection F18
or terminals X6.6/X6.7
(see page 172); replace
sensor if required.
Check resistance (Pt 500)
at plug-in connection F2 or
terminals X5.2/X5.3 (see
page 172); replace sen-
sor if required.