Viessmann Vitocal 350-A Installation And Service Instructions Manual page 141

Control unit diagnostics
Message
System characteristics Cause
«A7 Solar circuit
«A8 Pump heat. circuit 1
«A9 Heat pump
«AB Electric heater
(cont.)
No flow in solar circuit
(solar circuit pump stop-
ped)
No flow in heating circuit
A1 (circuit pump stop-
ped)
Heat pump fault
■ Heat pump faulty
■ Safety high pressure
switch has activated
■ High pressure or low
pressure sensor has
responded 8 times
within 24 h.
■ Fault EEV controller
■ Temperature sensors
in primary/secondary
circuit faulty
Fault, instantaneous
heating water heater
(appliance faulty or high
limit safety cut-out has
responded).
Troubleshooting
Measures
Check solar circuit pump
and replace if required
(see Vitosolic installation
and service instructions).
Test voltage at connection
2X7.9 and check pump
mechanically; replace if
required.
Scan further messages
("Message history" see
page 132); check flow
rates, motor currents/
motor protection, full wave
soft starter and safety
high pressure switch.
Note
After removing fault,
switch appliance OFF and
ON again once.
Danger
Contact with 'live'
components can
lead to severe
injury from elec-
tric current.
Isolate the power
supply prior to
starting work on
the appliance.
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