Potterton Promax System HE Installation And Servicing Instructions page 44

Is
230V S/L-N & L-E
at mains input
terminal block ?
YES
Is there
at least 18.1 mbar
dynamic at gas
valve inlet ?
YES
Is
condensate trap
blocked ?
NO
Reset lockout.
Does fan run ?
YES
Is
YES
there no spark
and no gas ?
(check at meter)
NO
YES
Is
there gas but no
spark ?
NO
YES
Is
there spark but no
gas ?
NO
Is
the detection
probe damaged ?
YES
Replace detection probe.
44
The polarity of the
NO
mains input to the
boiler is reversed. This
must be rectified.
NO
Incorrect gas
supply to boiler.
YES
Clear blockage and
dry sensors
NO
230V at control
PCB connection to
ignition PCB
Replace control PCB.
there 230V
at ignition PCB
connection to gas
valve (O) ?
Replace ignition PCB.
NO
14.0 Fault Finding
Ignition Lockout
Is there
YES
(M) ?
NO
Is
YES
NO
Is
YES
control PCB fan
connection 24 Vac
across (L) ?
NO
Replace control PCB.
Is
NO
spark probe
damaged ?
YES
Replace spark probe.
Is
YES
wiring from ignition
PCB to detection
probe OK ?
NO
Rectify wiring.