Central Heating Function; Ignition Sequence - Worcester GREENSTAR 25Si Instruction Manual

Room
thermostat and/or
mains
programmer ON
(or link fitted at
ST10)
POWER BLUE
AND
SWITCH LIGHT
Facia mounted
ON ON
programmer (if
fitted) ON
AND
CH control knob
ON
FAULT FINDING
& DIAGRAMS
3 minute wait
Fan to IGNITION
CENTRAL
start SEQUENCE
HEATING
DEMAND speed. (see detail)
Diverter valve
in CH position

IGNITION SEQUENCE

Pump ON.
Spark
ignition
4 seconds
NO
YES
5th
LOCKOUT
attempt?
Over temperature shut-
Gas valve OFF.
down if water tempera-
Fan overrun
ture is 5°C above set
30 seconds
Fan (& gas)
GREEN
10 second
FLAME
stabilisation
LIGHT
period.
temperature
ON
YES
BURNER
LIT?
NO
Stop spark.
Wait
10 seconds
value.
modulation
END OF
to achieve
BOILER
set
DEMAND
(40-82°C)
Gas valve
OFF
Pump run 3
minutes
Fan run 30
seconds