125
Fault mes-
sage
Cause Remedy Re-
set-
ting
"121: Flow
temp HC1"
Set flow temperature for
heating circuit 1 not reached
Check flow temperature sen-
sor and lead (see page 146).
Check that the flow tempera-
ture sensor is installed cor-
rectly.
"122: Flow
temp HC2"
Set flow temperature for
heating circuit 2 not reached
"127: Le-
gionella
temp"
Higher DHW temperature not
reached
Check temperature sensors
(see page 140).
Check the system pressure.
Vent the heating system.
Check whether there is any
throughput (code 8366 in di-
agnostics heat generation)
Check function of 3-way
diverter valve.
"157: Boiler
flow thermo-
stat"
Temperature limiter in the
safety chain has tripped.
Check the system pressure.
Vent the heating system.
Check whether there is any
throughput (code 8366 in di-
agnostics heat generation)
Check function of the circula-
tion pump.
Check function of 3-way
diverter valve.
UR
"158: Con-
densate"
Level switch has tripped. Check condensate drain,
clean siphon.
Check installation position
and function of the level
switch.
UR
Troubleshooting
Fault messages
(cont.)
5618 294 GB
Service
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