Viessmann FB2A Installation And Service Instructions For Contractors page 87

Fault codes
(cont.)
Fault code System characteris-
on the dis- tics
play
59 No DHW heating
92 No DHW heating
94 No DHW heating
9A No DHW heating
9C No DHW heating
9E Control mode
9F Control mode
A7 Control mode as per
delivered condition
A8 Burner blocked The
venting program is
started automatically
(see page 61)
Cause
Lead break, outlet
temperature sen-
sor
Short circuit, col-
lector temperature
sensor; connection
to the solar control
module
Short circuit, cylin-
der temperature
sensor; connection
to the solar control
module
Lead break, collec-
tor temperature
sensor; connection
to the solar control
module
Lead break, cylin-
der temperature
sensor; connection
to the solar control
module
No flow rate in the
collector circuit or
flow rate too low, or
temperature limiter
has responded
Solar control mod-
ule fault
Faulty program-
ming unit
Air lock in the inter-
nal circulation
pump or minimum
flow rate not ach-
ieved
Troubleshooting
Measures
Check sensors (see
page 96)
Check sensor & on the
solar control module.
Check sensor % on the
solar control module.
Check sensor & on the
solar control module.
Check sensor % on the
solar control module.
Check solar circuit pump
and solar circuit. Acknowl-
edge fault message.
Check solar control mod-
ule
Replace programming
unit
Vent the system if the fault
message continues to be
displayed
87