General
Hinweis
It is the law that any service work
must be carried out by a competent
CORGI registered engineer.
Before looking for a fault condition,
check that:
&
The mains electrical supply is tur-
ned on.
&
The clock and / or room thermostat
(if fitted) are calling for heat (CH
‘faults’ only).
&
The gas service cock is open.
&
The DHW (Combi only) and CH iso-
lation cocks are open.
&
The system is at design pressure.
Before attempting any electrical fault
finding, always conduct the prelimi-
nary electrical system safety checks.
On completion of any service or fault
finding operation involving making or
breaking electrical connections
always check for earth continuity,
polarity and resistance to earth.
Function sequence and possible faults
Display screen
Remedy
Control unit is-
sues heat de-
mand
No
Increase set value
and ensure heat is
drawn off
Yes
Fan starts
No
after approx. 51 s
Checking fan ca-
bles and plugs
Fault
F5/F9
Yes
Air pressure li-
miter enables
start (contact
closed between
terminals „X8.7“
and „X8.8“)
No after approx. 51 s Check fan cables
and fan plug-in
connections,
check fan
Fault
F5/F9
Yes
Ignition No Fault Check the con-
nection ignition
module
F4
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