Viessmann VITOCAL 350-A, Installation And Service Instructions Manual

Page: 141 / 256

141
Message
System characteristics Cause Measures
«
A7 Solar circuit
No flow in solar circuit
(solar circuit pump stop-
ped) Check solar circuit pump
and replace if required
(see Vitosolic installation
and service instructions).
«
A8 Pump heat. circuit 1
No flow in heating circuit
A1 (circuit pump stop-
ped) Test voltage at connection
2X7.9 and check pump
mechanically; replace if
required.
«
A9 Heat pump
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
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.
«
AB Electric heater
Fault, instantaneous
heating water heater
(appliance faulty or high
limit safety cut-out has
responded).
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.
Troubleshooting
Control unit diagnostics
(cont.)
5414 828 GB
Service