Repairs; Shutting Down The Boiler - Viessmann VITODENS 200-W Installation And Service Instructions For Contractors

Fault messages
(cont.)
Displayed fault System characteristics
code
F.548 Mixer closes. Heating circuit
pump is operational.
F.549 Mixer closes. Heating circuit
pump is operational.
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.
Cause
Short circuit, flow temper-
ature sensor for heating
circuit 4 with mixer
Short circuit, flow temper-
ature sensor for heating
circuit 4 with mixer
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
Measures
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.
Check flow temperature sensor,
mixer 4.
Measure voltage at sensor input on
electronics module. Set value:
3.3 V with sensor disconnected.
–
103