F
A
UL
T
F
IND
IN
G
& DIA
G
RAM
S
FAULT FINDING
INSTALLATION & SERVICING INSTRUCTIONS FOR WORCESTER GREENSTAR HEATSLAVE 12/18-18/25-25/32
6 720 802 432 issue A 04/2012
52
These fault finding charts are provided to assist
competent and suitably qualified engineers to locate and
rectify faults. Whilst every effort has been taken to ensure
the information given is correct and complete we cannot
guarantee that every eventuality has been covered.
Worcester, Bosch Group cannot be held responsible for
costs incurred by persons not deemed to be competent.
BURNER
FIRES WHEN
PHOTOCELL IS
COVERED?
APPROX
35Ω ACROSS BLUE
& BLACK MOTOR
WIRE?
MOTOR
STARTS AFTER
INITIALIZATION
CHECK TIME 3.5s?
CONTROL BOX IS
SUPPLIED
WITH HEAT
DEMAND
REPLACE
PUMP
COUPLING
WASHING
PRESSURE
1 - 2 BAR?
DRIVE COUPLING
BROKEN?
FAN RUNS FOR
LESS THAN 12s?
CHECK OIL
SUPPLY TO OIL
PUMP
FAN MOTOR OR
OIL PUMP
SEIZED?
REPLACE
OIL PUMP
REPLACE
SEIZED
COMPONENT
REPLACE
MOTOR
CAPACITOR
CHECK BOILER
& SYSTEM
CONTROLS
REPLACE FAN
MOTOR AND
CHECK CONTROL
BOX
230V TO MOTOR
ACROSS BLUE &
BLACK WIRE?
MOTOR GIVES
5OVac ACROSS
WHITE & BLACK
WIRE?
SOLENOID COIL
RESISTANCE
90 to 110 Ω?
REPLACE
SOLENOID COIL
A
BURNER LOCKS
OUT AFTER 25s?
Y
N
N
Y
Y
N
N
N
Y
Y
N
N
N
Y
Y
Y
N
N
Y
Y
N
Y
N
SOLENOID COIL
LEAD OK?
REPLACE
SOLENOID COIL
LEAD
Y
N
Y
N
REPLACE
FAN MOTOR
PHOTOCELL
RESISTANCE >10
MΩ IN DARK AND
<10 kΩ IN LIGHT?
REPLACE
PHOTOCELL
REMOVE
EXTRANEOUS
LIGHT
Y
B
D
RED 0.5s ON / RED 0.5s OFF
Lock-out for false flame signal
RED 0.2s ON / RED 0.2s OFF
Lock-out for max n° of recycles
RED 2.5s ON / ORANGE 0.5s ON
Lock-out for fan motor failure
RED steady ON
Lock-out for no flame aer safety
me
ORANGE 0.5s ON / GREEN 0.5s ON
Lock-out for eeprom failure
RED 2.5s ON/ GREEN 0.5s ON
Lock-out for oil-valve failure
F
D
E
B
C
GO TO
BOX
CONTROL BOX IN LOCKOUT
LED CODE - LOCKOUT TYPES
A
GREEN 0.5s ON / RED 0.5s ON
Anomaly for presence of
extraneous light
ORANGE steady ON
Anomaly for presence of
abnormal frequency supply
ORANGE 0.2s ON / GREEN 0.2s ON
Control box internal error
GREEN 0.2s ON / RED 0.2s ON
Anomaly for reset push-buon or
remote reset failure
Lock out aer 25s
When anomaly appears during pre-purge,
burner remains in pre-purge.
When anomaly appears aer ignion, burner
remains in operaon.
When anomaly disappears burner restarts.
Remote reset / push buon is acvated for
more than 60s.
When anomaly appears burner doesn't stop
CONTROL BOX IN STANDBY
LED CODE - ANOMALY TYPES
GREEN 0.5s ON / GREEN 2.5s OFF
Pre-heang me
Fit pre-heater link
RIELLO
MO535 MRF
DIGITAL
CONTROL BOX
FAULT FINDING
LOGIC