Fault Finding & Diagnosis; Fault Finding - Worcester Greenstar 12i System Instruction Manual

FAULT FINDING
NOTE : This fault finding information is for guidance only. Worcester 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 at different rates during 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).
PREUMI NARY CHECKS :Preliminary elec1rical system checks are the first electrical checks to be carried out during a fault-finding
procedure. On oompletion 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.
Blue light Lockout reset
Fault Possible solution/check
indication
button
Off
Off
No power at control board
PE!rmanent mains supply to boiler.
Boiler mains sw itch.
Fuse F1, 2.5A or Fuse F3, 0.5A
Tt3nsformer (both coils below 100Q).
Otherwise replace control board.
On
Off
Boiler not operati()Q during
External dfvetter valve.
central heating dem&nd External timer or room stat
(HWok) OR
If optional diverter valve is fitted:
Temperature control in frost protection position.
Live demand at ST1o-LR (extemal CH demand).
Facia mounted timer
(if
fitted).
Diverter v;J.Ive.
Control boerd.
Boiler operating
Some older thermos tats (contair\ing capacitors) may give a low
without live dQmand at voltage retum at ST 10·LR when the themlostat contacts are open.
ST1 0-l.R (from external
Check tha.t there
fa
not a permanent live at ST10·LRfrom another
roomsta.t timer).
$0UfC9.
Boiler not opecating during
ExternaJ diverter valve.
hot watar demand (CH
ok). External timer or cylinder s tat
OR
If
optional d lverter valve
ls fitted:
Short circuit acrosa ST8 from cylinder s taVtimer.
Facia mounted timer (if fitted).
Oiverter
valve.
Contro l board.
Boiler not opBrating during Temperature control in fros t protection position.
any demand.
Live demar\d at ST10.LR {from extemal system).
Control board.
OR
If optional diverter valve Is
fitted:
Timer.
Control board.
S low flash
Flashing (reset r&quired)
Ignition lockout
Gas present and at correct pressure.
(normally off,
Combustion
co
2
level.
Flue condition.
flashes on)
Ignition electrodes
I
harness
I
connections.
Gas valve (coils 140 · 1900) / low voltage harness connection.
Otherwise replace C()(ltrol board .
S low flash Flashing (reset requi-red)
A ue Ov9Iheat
Heat exchanger blocked.
(normally on,
Heat cxchangCI baffle$ removed and not refitted.
flashes oH)
Heat exchanger overheat
Water pressure.
All air vented.
Pump
I
harne$S
I
connections.
Water leak&
I
blockages.
Safety thermostats /low voltage
wiring
harness
I
connections.
Otherwise reoJa.ce control board.
Rue blockage
Blockage in flue system.
Fast flash Off
VotatiJe lookout
Temperature sensor {8000·20,0000).
Low vohage wiring harness
I
COMections to senSOt.
Fan
I
fan hamess
I
connections to
tao.
Code plug fitted.
Fast flash
Ftashina
Internal fault
Replace oontrol boerd
2 pulses
No
r ~ght
Not a fault code
SeMoe mode selected to min,
press
service button to retum to normal.
5 pulses
No light
1
Not a taun code
Servioe mode selected to max, press service button to retum to normaJ.
FAULT FINDING
INS'W.WIOii & SEII'ACINGitiSTRUCfiCNSFOQ\'ORCESTERGAEEHSfAR 1,;
Syt~i9Jrio"'
&716112~fWOEO
rwoRCESTER
"""" ""'