BOILER FUNCTION
NO
YE
S
PO
WE
R
SW
IT
CH
ON
BOI
L
E
R
DE
MAN
D
F
an to
start
speed.
Diverter valve
in C
H
position
P
ump O
N
.
IG
N
ITI
O
N
SE
QU
E
N
CE
(see detail)
BL
UE
LI
G
H
T
ON
BURNER
L
IT?
GREEN
F
LAM
E
LI
G
H
T
ON
Stop spark.
W
ait
10 seconds
5th
attempt?
L
O
CK
OUT
10 second
stabilisation
period.
F
an (& gas)
modulation
to ac
hieve
set
temperature
(4
0-82°
C)
E
N
D OF
BOI
L
E
R
DE
MAN
D
Gas valve
OFF
P
ump run 3
minutes
F
an run 3
0
seconds
Over temperature shut-
down if water tempera-
ture is 5°
C ab
ove set
value.
Gas valve O
F
F.
F
an overrun
3
0
seconds
3 minute wait
Spark
ignition
4 seconds
NO
YE
S
BOILER FUNCTION
INSTALLATION & SERVICING INSTRUCTIONS FOR WORCESTER BOSCH GREENSTAR 12i System/24i System
8 716 107 375a (02/05)
56
FA
U
LT
F
IN
D
IN
G
& D
IA
G
R
A
M
S
System demand
at S
T10
AND
temperature
control knob
ON
IG
N
IT
ION
SEQU
E
N
C
E
IMPORTANT: IF THE OPTIONAL
INTEGRAL DIVERTER VALVE HAS
BEEN FITTED
Disregard this and the following page and
refer to the correct versions for CENTRAL
HEATING and DHW FUNCTIONS in the
ADDITIONAL INFORMATION section at the
back of this book.
