Technical data

YES
15.0 Fault Finding
49
Is there gas at gas valve
inlet ?
Check isolation valve
and gas supply.
YES
NO
Ignition Lockout
Reset Lockout.
When the Burner On light
is on, is there gas flow
(check at meter) ?
Unplug
Gas Valve,
is there 215 Vdc at F
when the Burner On light
is on ?
Is
spark or flame detection
probe damaged ?
Have
boot lace seals
inside combustion box
door grown outwards so door
held away from
heat exchanger ?
Is
the burner
damaged or the burner
gaskets missing/damaged or
the wrong burner
fitted ?
Replace Main PCB.
Set spark gap to
3.5mm.
Replace Gas Valve.
Trim back seals
Replace Burner or
burner Gaskets.
Rectify wiring and check
spades and receptacles
for a firm fit.
Replace PCB if fault
persists. Replace gas
valve.
YES
YES
NO
NO
YES
Remove Gas Valve & check
inlet filter for blockage.
Check gas feed pipe seals,
venturi gasket & fan seals
are fited and not damaged.
Otherwise incorrect gas
supply to boiler.
Is
there at least
18mbar dynamic at gas
valve inlet ?
F
Gas Valve Plug
(when unplugged)
Is
there 240Vac at G
when the Burner On
light is on ?
Lead from PCB to Gas
Valve faulty.
Is
spark gap between 3 and
4mm ?
Replace spark or flame
detection probe and
gaskets.
NO
Is
wiring from PCB
to spark probe & flame
detection probe OK & are
terminals tight ?
Mains Input
Transformer
Burner On
&
Fault Neons
Pump
Diverter Valve
Gas Valve
Modem PCB
Room Thermostat
Flow &
Return
Thermistors
Overheat
Thermostats
&
Flow Switches
&
Condensate Trap
Room Control
Display PCB
Fan
G
NO
NO
YES
YES
NO
YES
NO
YES
YES
NO
NO