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Wait
5 seconds
IGNITION
SEQUENCE
(see detail)
PREHEAT AND DHW FUNCTION
NO
YES
POWER
SWITCH
ON
Tap open
(recognised
by flow
turbine)
Diverter valve
in DHW
position
Pump ON.
BLUE
LIGHT
ON
BURNER
LIT?
Fan to
start
speed.
Stop spark.
Wait
10 seconds
5th
attempt?
LOCKOUT
Fan (& gas)
modulation
to achieve
set
temperature
(40-60°C)
DEMAND
END
Gas valve
OFF
Pump run 3
minutes
Fan run 30
seconds
Over temperature shut-
down if water tempera-
ture is 8°C above set
value.
Gas valve OFF.
Spark
ignition
4 seconds
NO
YES
ECO button
not
illuminated *
(ie preheat
requested)
AND
20 minutes
since last pre-
heat demand
AND
temperature
at least 10°
below set
point.
PREHEAT
DEMAND
DOMESTIC
HOT
WATER
DEMAND
(priority over
all other
demands)
GREEN
FLAME
LIGHT
ON
Burner shut down if
primary temperature
94°C
(until 84°C)
Fan (& gas)
modulation
to achieve
(55°C)
DEMAND
END
Gas valve
OFF
Stop pump
Stop fan
IGNITION SEQUENCE
*Set by
pressing ECO button. If pro-
grammer is fitted this is set by
a combination of programmer
(DHW) demand and ECO
button.
PREHEAT AND DHW FUNCTION
INSTALLATION & SERVICING INSTRUCTIONS FOR WORCESTER GREENSTAR 24 i junior/28 i junior
8 716 107 336b (11/05)
57
FAULT FINDING
& DIAGRAMS