Operating instructions

ManualsBrandsViessmann ManualsHeat PumpVITOCAL 242-G

49

Message

System characteristics Cause Measures

10 Outside temp sensor

Operation with outside

temperature -40 °C

Short circuit, outside

temperature sensor

Check resistance (Ni 500)

at plug-in connection F0;

replace sensor if

required.

18 Outside temp sensor

Operation with outside

temperature -40 °C

Lead break, outside tem-

perature sensor

Check resistance (Ni 500)

at plug-in connection F0;

replace sensor if

required.

20 Flow sensor secondary

Operation with tempera-

ture value of return tem-

perature sensor in sec-

ondary circuit, plus 5 K. If

both temperature sen-

sors (secondary flow and

return) are faulty, the

heat pump stops (mes-

sage A9)

Short circuit, secondary

circuit flow temperature

sensor

Check resistance (Pt 500)

at plug-in connection F8

and terminals X5.8/X5.9;

replace sensor if

required.

21 Return sensor sec.

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 stops (mes-

sage A9)

Short circuit, secondary

circuit return tempera-

ture sensor

Check resistance (Pt 500)

at plug-in connection F9

and terminals X5.10/

X5.11; replace sensor if

required.

28 Flow sensor secondary

Operation with tempera-

ture value of return tem-

perature sensor in sec-

ondary circuit, plus 5 K. If

both temperature sen-

sors (secondary flow and

return) are faulty, the

heat pump stops (mes-

sage A9)

Lead break, secondary

circuit flow temperature

sensor

Check resistance (Pt 500)

at plug-in connection F8

and terminals X5.8/X5.9;

replace sensor if

required.

Troubleshooting

Messages

(cont.)

5441 603 GB

Service