Glow-worm SwiftFlow 120 Servicing Instructions page 12

Before commencing tests isolate the boiler, make sure that the remote controls are not calling for duty and there
Remove the outer case, control housing and it's cover.
Check all connections on the control board and the boiler components, rectify or renew as necessary.
Two dummy two way connectors are provided for ease of testing continuity.
Remove fuses and test for continuity, if faulty, check cables and connections for shorting to E or N, rectify if
necessary and replace fuse, with spare provided.
Check central heating water pressure, repressurize if necessary.
Make sure boiler is cold. Check all pipes and connections between the Air Pressure Switch (APS) fan and
combustion sample point, also between fan and gas/air ratio unit. Make sure sample point cap is fitted correctly.
Make sure the pilot is alight. Make sure venturi is not blocked.
Isolate supply
YES
remove CN6 is
there continuity
between
Red and Violet?
NO
Faulty APS.
Replace.
YES
Is there continuity at CN2
on the fan driver pcb
between White and the
fan motor laminations?
(repeat with Grey and
continued
Purple)
(a)
221045A
Supplied By www.heating spares.co Tel. 0161 620 6677
3 F a u l t F i n d i n g
Carry out the initial fault finding checks described in Section 3.1.
Check that gas, water and electricity are available at the boiler.
is no domestic hot water demand.
Replace CN6.
With no demand to the boiler.
Restore power.
Does the mains Orange LED
come on?
YES
YES
Does the boiler light?
NO
Does fan run at full
speed for approx
30 seconds?
NO
Isolate supply.
NO
Restore supply.
During the 30 second is
there approx 26V ac on
Black and Red from the
transformer at CN1?
YES
NO
Is there 26V ac on
Orange and Yellow at
CN7 and greater than 3V
dc on Grey and Purple?
YES
Isolate supply. Is the
NO
resistance at CN2 on the
fan driver pcb between
White and Grey, Grey
and Purple, Purple and
White approx 2.5Ω ?
YES
YES
NO
NO
Is there 240V ac at
Blue and Brown on CN3.
YES
Faulty LED.
Does not effect
boiler operation.
Isolate supply, is there
continuity at flow switch?
NO
Faulty main PCB.
Replace.
Faulty transformer.
Replace.
Faulty main PCB.
Replace.
Faulty fan.
Replace.
Faulty fan.
Replace.
Faulty fan driver
pcb. Replace.
12
NO
Check electricity
supply.
YES
Faulty flow switch.
Replace.
Diagram 3.8