Viessmann B2HF - Repairs; Shutting down the Boiler

103
Displayed fault
code
System characteristics Cause Measures
F.548 Mixer closes. Heating circuit
pump is operational.
Short circuit, flow temper-
ature sensor for heating
circuit 4 with mixer
■
Check flow temperature sensor,
mixer 4.
■
Measure voltage at sensor input
on electronics module. Set value:
3.3 V– with sensor disconnected.
■
Check commissioning assistant
setting.
■
Checking setting of ADIO rotary
switch.
F.549 Mixer closes. Heating circuit
pump is operational.
Short circuit, flow temper-
ature sensor for heating
circuit 4 with mixer
Check flow temperature sensor,
mixer 4.
Measure voltage at sensor input on
electronics module. Set value:
3.3 V
–
with sensor disconnected.
Note
If subscriber faults occur, "Fault, subscriber ..." is dis-
played.
Repairs
!
Please note
Residual water will escape when the boiler or
one of the following components is fitted or
removed:
■
Water-filled pipework
■
Heat exchanger
■
Circulation pumps
■
Plate heat exchanger
■
Components fitted in the heating water or
DHW circuit.
Water ingress can result in damage to other
components.
Protect the following components against
ingress of water:
■
Control unit components (especially in the
service position)
■
Electrical components
■
Plug-in connections
■
Cables and leads
Shutting down the boiler
1. Switch OFF the power supply.
2. Shut off the gas supply.
3. If the boiler needs to be removed:
■
Disconnect the balanced flue system.
■
Drain the boiler on the heating water and DHW
sides.
■
Disconnect the on-site cables/leads.
Troubleshooting
Fault messages (cont.)
5593201
Diagnosis