BOILER FUNCTION
6 720 645 222a (2012/05)
17
7.2
BOILER FUNCTION
Fig. 21 Boiler function
NO
YE
S
MAI
N
S
PO
WE
R
S
U
PPL
Y
ON
BOILER
DE
MAN
D
F
an to
start
speed.
P
u
mp 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
FL
A
M
E
LI
G
H
T
ON
Stop spark
and gas.
Wa
it
10 seconds
5th
attempt?
LO
C
K
O
U
T
10 second
stabilisation
period.
Fa
n
modulation
to ac
hieve
set
temperature
(4
0-82°
C)
END
O
F
BOI
L
E
R
DE
MAN
D
Gas valve
OFF
P
u
mp 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 pump
over run
Spark
ignition
and gas
4 seconds
NO
YE
S
Room
thermostat and/or
mains
programmer O
N
(or link fitted at
S
T
10)
AND
F
a
cia mounted
programmer (if
fitted) O
N
AND
C
H
control knob
ON
IG
N
IT
ION
SEQU
E
N
C
E
6720645222-25.1W
o
Diverter valve
CH position down
Cylinder position up
