Potterton Promax 15 HE Installation And Servicing Instructions page 40

NO
Reset lockout,
does fan run ?
YES
Is
YES
there no spark and
no gas (check at
meter) ?
YES
YES
Is
there gas but
no spark ?
NO
YES
Is there spark
but no gas ?
NO
Is
NO
18.1mbar
dynamic at gas
valve inlet ?
NO
Incorrect gas
supply to boiler.
M
N
O
br
r
Ignition
b
PCB
b
br
Detection Electrode
w
g/y Gas
br
Valve
Condensate
g/y
Trap
g/y
Spark
Electrode Q
S/L
Mains
40
Input
Supplied By www.heating spares.co Tel. 0161 620 6677
Ignition Lockout
Does
control PCB fan
connection have
12 Vac across it
(L) ?
NO
Replace control PCB.
Is there
230V at control
PCB connection to
ignition PCB
(M) ?
NO
Replace control PCB.
Is
spark probe
damaged ?
YES
Replace spark probe.
Is there
230V at ignition PCB
connection to gas
valve (O) ?
NO
Replace ignition PCB.
Is the detection
probe damaged ?
YES
Replace detection
probe.
Control
PCB
R
L
bk bk
b bk g
w br
v
r
b
DC
w
Dry Fire Fan
bk
b br
Flow Switch
r
r
Transformer
bk
br On/Off
Thermistor
Switch
Casing
Stat
bk
bk
N P/F Overheat Stat
Optional
Pump Feed
15.0 Fault Finding
Does
YES
fan
connection have
12 Vac across it
(K) ?
NO
Wiring from control
PCB to fan faulty.
Is
YES there 230V
at ignition PCB
connection to control
PCB (N) ?
NO
Wiring from control PCB
to ignition PCB faulty.
Is
NO
spark gap
between 3 and
5mm ?
NO
Set spark gap to 4mm.
Is there
YES
230Vdc at the end of
the gas valve lead ?
(P)
NO
Replace gas
valve lead.
Is
YES
wiring from ignition
PCB to detection
probe OK ?
NO
Rectify wiring.
Burner on, wiring from
ignition PCB to control
PCB faulty.
K
Fan Connection
when unplugged
YES
Replace fan.
Replace ignition PCB.
YES
YES
Is ignition PCB
fuse OK ?
NO
Check for short
circuits on ignition
PCB and gas valve
if OK replace fuse.
Is
YES
wiring from ignition
PCB to spark probe
OK ?
NO
Rectify wiring.
YES Is
sensing tube
blocked ?
NO
Replace gas
valve.
Is there
YES
230V, ignition PCB
burner on pin to
control PCB
(Q) ?
NO
Replace ignition PCB.
Is there
NO
230V control PCB
burner on pin to
ignition PCB ?
(R)
P
YES
Replace ignition
PCB.
YES
Unblock tube.
YES
YES
Replace control
PCB.