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CENTRAL HEATING FUNCTION
NO
YES
POWER
SWITCH
ON
CENTRAL
HEATING
DEMAND
Fan to
start
speed.
Diverter valve
in CH position
Pump ON.
IGNITION
SEQUENCE
(see detail)
BLUE
LIGHT
ON
BURNER
LIT?
GREEN
FLAME
LIGHT
ON
Stop spark.
Wait
10 seconds
5th
attempt?
LOCKOUT
10 second
stabilisation
period.
Fan (& gas)
modulation
to achieve
set
temperature
(40-82°C)
END OF
BOILER
DEMAND
Gas valve
OFF
Pump run 3
minutes
Fan run 30
seconds
Over temperature shut-
down if water tempera-
ture is 5°C above set
value.
Gas valve OFF.
Fan overrun
30 seconds
3 minute wait
Spark
ignition
4 seconds
NO
YES
Room
thermostat and/or
mains
programmer ON
(or link fitted at
ST10)
AND
Facia mounted
programmer (if fit-
ted) ON
AND
CHcontrol knob
ON
IGNITION SEQUENCE
CENTRAL HEATING FUNCTION
INSTALLATION & SERVICING INSTRUCTIONS FOR WORCESTER GREENSTAR 24 i junior/28 i junior
8 716 107 336b (11/05)
56
FAULT FINDING
& DIAGRAMS