Potterton Promax System HE Installation And Servicing Instructions page 39

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