Viessmann VITOCAL 250-A - Page 124

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F.798 Mechanical fault, circulation pump, heating circuit 2
F.798
System characteristics
Heating circuit pump, heating/cooling circuit 2 is off.
No room heating, heating/cooling circuit 2
Cause
Mechanical fault on heating circuit pump, heating/cool-
ing circuit 2, e.g. impeller blocked
Measures
1. At the centre of the pump casing, press the coupling
and simultaneously turn the pump shaft.
2. Check the impeller. Remove the rotor if necessary.
Remove dirt. Flush and vent the system if neces-
sary.
3. Other pump noises:
■
Gurgling: Vent system again.
■
Hissing, or circulation pump getting hot: Check set
pump rate. Adjust if necessary.
■
Knocking or rattling: Replace the circulation pump.
F.799 Electrical fault, circulation pump, heating circuit 1
F.799
System characteristics
Secondary pump/heating circuit pump, heating/cooling
circuit 1 is off. Status indicator on circulation pump,
LED lights up red.
■
No room heating, heating/cooling circuit 1
■
No DHW heating
Cause
Electrical fault on secondary pump/heating circuit
pump, heating/cooling circuit 1
Measures
1. Check system fuse. Replace the fuse if necessary.
2. Check connecting cable, connections and plug-in
connections on EHCU electronics module. Replace
connecting cable if necessary:
■
230 V connection: X6.1 to X6.3
■
PWM connection: X7.1 to X7.3
3. Replace the circulation pump.
F.800 Electrical fault, circulation pump, heating circuit 2
F.800
System characteristics
Heating circuit pump, heating/cooling circuit 2 is off.
Status indicator on circulation pump, LED lights up red.
No room heating, heating/cooling circuit 2
Cause
Electrical fault on heating circuit pump, heating/cooling
circuit 2
Measures
1. Check system fuse. Replace the fuse if necessary.
2. Check the following connections to the EHCU elec-
tronics module:
■
230 V connection: X25.1 to X25.3
■
PWM connection: X26.1 to X26.3
■
Check wires and plugs for correct seating.
■
Check connections for contact corrosion.
■
Check cables for mechanical damage, e.g. crush-
ing, kinking, chafing or breakage.
Replace connecting cable if necessary.
3. Replace the circulation pump.
F.801 Malfunction, refrigerant circuit reversal valve
F.801
System characteristics
Fault, outdoor unit, no refrigerant circuit reversal
Cause
■
4-way diverter valve faulty
■
Refrigerant leak
■
High pressure sensor faulty
Messages
Fault messages (cont.)
6218234
Diagnosis