FAULT
FINDING
NOTE: This fault finding information is for guidance only.
Worcester
Bosch cannot be held responsible for
costs
incurred by persons not deemed
to
be
competent.
The electronic control system for this boiler incorporates a blue central indicator. This normally confirms the permanent mains supply but, by flashing dur-
ing a fault, provides a guide
to
the cause as listed.
This fault finding system assumes that the appliance has been operating normally until the time
of
failure (i.e. not a first installation error).
PRELIMINARY CHECKS: Preliminary
electrical
system
checks
are the
first
electrical
checks
to
be
carried
out
during
a
fault-finding
procedure.
On completion
of
the Service/Fault-Finding task which has required the breaking and remaking
of
electrical connections,
check
(a)
EARTH CONTINUITY, (b)
SHORT
CIRCUIT
CHECK,
(c) POLARITY and (d)
RESISTANCE
TO EARTH.
An optional text display is avaliable which gives a text description
of
the service functions
of
the boiler
Display code
Description
Remedy
A7
Hot
water
NTC
sensor defective.
Check
hot water
NTC
sensor and
connecting
lead for
circuit breaks/short circuits.
AS
Break
in
communication
to
TD200
or/and RT10.
Check
electrical connections.
b1
Code
plug
not
detected. Insert
code
plug correctly,
test
and replace if necessary.
C6
Fan
speed
too
low.
Check
fan lead
and
connector,
and
fan;
replace
as
necessary.
E2
CH
flow
NTC sensor defective.
Check
CH
flow
NTC sensor and connecting lead.
E9
Safety temp. limiter
in
CH
flow
has tripped.
Check
system
pressure,
check
safety
temp.
limiters,
check
pump
operation,
check
fuse on pcb, bleed appli-
ance.
EA
Flame not detected. Is
gas
cock
turned
on?
Check
gas
supply
pressure,
power
supply,
igniter
electrode
and
lead,
ionisation
sensing electrode and lead, flue
duct
and
C02
level.
FO
Internal error.
Check
electrical connector contacts, programmer inter-
face
module ignition leads are not loose; replace
pcb
if
necessary.
F7
Flame
detected
even though appliance switched off.
Check
electrode assembly, dry pcb. Flue clear?
FA
Flame
detected
after
gas
shut off.
Check
gas valve and wiring
to
gas valve. Clean conden-
sation trap and
check
electrode assembly. Flue clear?
Fd
Reset button pressed by mistake. Press reset button again.
More
detailed fault finding procedures are described
in
the Service booklet for the Engineer number 6
720
612 361.
FAULT
FINDING
INSTALLATION & SERVICING INSTRUCTIONS
FOR
WORCESTER BOSCH GREENSTAR
25CDI/30CDI/37CDI/42
co;
~ORCESTER
6 720
613
700a
(2006/11)
Bosch
Group
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