14.0 Fault Finding
39
Is
boiler supply
fuse OK ?
Is there
230 V at mains
input terminal
block
(A)
?
Is
there 230 V at
mains input connection
to control PCB
(B)
?
Is
there 230 V at
control PCB transformer
mains connection
(C)
?
Is
control PCB
fuse F2 OK ?
Is wiring
from control PCB
to interface PCB
OK
(E)
?
Does
boiler produce
heat ?
Replace with 3A fuse.
No mains supply to
boiler.
Wiring from mains input
terminal block to control
PCB faulty.
Replace control PCB.
Replace transformer.
Check for short circuits
on control PCB and fan.
If OK replace fuse.
Rectify wiring
Replace control PCB.
Replace interface PCB.
YES
NO
Is there
24 V ac at control
PCB transformer 24V
connection
(D)
?
NO
NO
NO
NO
NO
NO
NO
YES
YES
YES
YES
YES
YES
YES
Mains LED Off
Spark
Electrode
Ignition
PCB
Control
PCB
Condensate
Trap
Detection Electrode
Gas
Valve
Mains
Input
Optional
Pump Feed
Transformer
Overheat
Stat
Casing
Stat
Thermistor
Dry Fire
Flow Switch
DC
Fan
User PCB
br
br
w
g/y
g/y
br
b
b
b
b bk
br
bk
bk
bk
bk
bk
r
r
r
br
g
w
N P/F
bk
S/L
Pump
L
N
br
b
o o o o o o o o
g/y
br
r
b
bk
Earth
Electrode
A
B
C
D
E