Viessmann B0KA - Repairs; Shutting down the Boiler

74
Displayed fault
code
System characteristics Cause Measures
980 No DHW heating Water flow rate below min-
imum level
Check that the cylinder flow and
return are open.
Check DHW setting in commis-
sioning assistant and correct if
necessary.
Check pump. Replace if necessary.
Pause time for DHW heating can
be terminated by mains reset.
981 No DHW heating Water flow rate below min-
imum level
Check that the cylinder flow and
return are open.
Check DHW setting in commis-
sioning assistant and correct if
necessary.
Check pump. Replace if necessary.
Pause time for DHW heating can
be terminated by mains reset.
982 No central heating, no DHW
heating
Circulation pump heating
circuit 1 running dry
Check diaphragm expansion ves-
sel and circulation pump.
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. Turn off the power supply at the ON/OFF switch.
2. Shut off the gas supply.
3. If the boiler needs to be removed:
■
Isolate the system from the power supply, e.g. by
removing the separate fuse or by means of a
mains isolator, and check that it is no longer live.
■
Safeguard the system against reconnection.
■
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.)
6179762
Diagnosis