Glow-worm SwiftFlow 120 Servicing Instructions page 14

YES
(a)
Turn the DHW flow off.
Turn on the CH.
Does pump run?
NO
Faulty main PCB.
Replace.
221045A
Supplied By www.heating spares.co Tel. 0161 620 6677
3 F a u l t F i n d i n g
YES
(b)
Isolate supply disconnect Red in line connectors to
flow switch, is there continuity across flow switch?
Reconnect flow switch,
disconnect Purple in line
connectors to DHW thermistor.
Is the resistance between
8KΩ and 11KΩ?
YES
Faulty LED.
Does not
effect boiler
operation.
Restore supply.
NO
Is there about 24V
ac multifunctional
control?
YES
Faulty
multifunctional
control.
NO
YES
Is burner pressure
about 5.6mb?
YES
SYSTEM O.K.
14
NO
(c)
YES
YES
NO
Faulty DHW thermistor.
Replace.
Isolate supply, remove
CN1. Is there continuity
across DHW O/H stat?
YES
Is there continuity across
C and N/O at low water
pressure switch?
YES
Faulty main PCB.
Replace.
NO
Faulty flow switch.
Replace.
NO
Faulty DHW O/H stat.
Replace.
NO
Faulty water
pressure switch.
Replace.
Diagram 3.8 cont.