33
Open gas cocks
Contact the Gas
Supplier
Replace faulty bulb
Switch on bulbs
Isolate mains
Replace resistor
Fire satisfactory
Change the electro
magnetic unit
Change pilot
assembly
Is
thermocouple
output within limits ?
(9.4 - 13mV)
Is
meter pressure
correct ?
YES
NO
NO
YES
NO
Pipework
undersized or
restricted
Is
supply pressure
at appliance
correct ?
NO
YES
YES
YES
YES
NO
NO
NO
NO
YES
YES
YES
NO
YES
Are
gas cocks fully
open ?
Replace both
bulbs
Does one
bulb light?
Do
both bulbs
light ?
Are
plug & socket
(under spark
generator)
connected?
230v
across micro-
switch when
operated ?
230v across
resistor ?
Are bulbs
switched on ?
NO
NO
YES
YES
YES
YES
Are
pilot flames
stable and approx
20mm long
YES
Isolate mains
Rectify flue
YES
NO
Connect plug
and socket
Replace switch
Make good the
connection
Is
thermocouple
connection
sound ?
NO
Change pilot
assembly
Is
thermocouple
tip
sound ?
NO
Clean
thermocouple tip
Is
thermocouple
tip
clean ?
NO
Does
the fire remain
alight ?
Is
poor flue
pull, downdraught
or blockage evident, or
flue otherwise
unsound?