Unit installation

10.0Fault Finding
27
WARNING: Where practicable fault finding
should be performed with the main electricity
supply ISOLATED.
Is
pilot/ASD
assembly,sensing
tube or dilution hole
blocked or
damaged?
Check gas pressure at
inlet to valve (20mb)
Check for mains voltage
at pilot solenoid
Check electrode spark gap
(2.5 - 4.0mm)
Clear blockage, or
replace pilot/ASD
assembly or
sensing tube.
Check solenoid
leads for continuity
Replace wiring
harness
Check gas valve is
operating correctly
Replace P.C.B.
YES
YES
YES
YES
YES
NO
NO
NO
NO
NO
NO
Disconnect red + blue
leads & check resistance
of pilot solenoid
(approx. 1.5 K OHM)
Replace pilot
solenoid
Does
pilot burner
ignite ?
Does pilot
remain alight and ignition
sparking stop?
Check gas pressure at
inlet to valve (20mb)
YES
YES
NO
Rectify flue
Is
flue pull O.K. ?
Replace P.C.B.
YES
Is
pilot flame picture
O.K. ?
Replace P.C.B.
YES
Clear blockage, or
replace pilot/ASD
assembly or
sensing tube.
Is
pilot/ASD
assembly,sensing
tube or dilution hole
blocked or
damaged?
Replace lead
Is
sensing lead
continuity and insulation
O.K. ?
YES
25mm
16mm