Glow-worm Swift flow 80 Instructions For Use Installation And Servicing page 37

Continued
YES
Isolate supply. Is there
YES
continuity between
P.C.B. and modulator?
NO
Rectify as necessary.
Faulty modulator,
replace.
Isolate supply. Remove block 4 from
P.C.B. As boiler cools does resistance
across 'D.H.W. thermistor' pins on
block 4 increase from approx
2.5K Ω to 10KΩ ?
NO YES
Faulty thermistor, replace.
Is there between 15 and 30V
DC across 'modulator' pins on
block 1 on P.C.B.?
YES
Isolate supply. Remove
connectors from modulator. Is
resistance across modulator
between 120 and 140 Ω?
NO YES
Faulty modulator,
replace.
Check continuity from
P.C.B. to modulator.
Rectify if necessary.
Faulty P.C.B., replace.
Is there between 4 &
15V DC across
modulator pins on
NO
block 1 on P.C.B.?
YES
Faulty modulator, replace.
Faulty thermistor, replace.
Isolate supply. Remove
block 1 from P.C.B. Is
resistance across
modulator pins on
block 1 between 120
NO
& 140 Ω?
YES
Faulty P.C.B., replace
Faulty modulator, replace.
3 Fault Finding
Continued
YES
Reduce D.H.W. flow to
3.7 litres/minute. Does
burner pressure reduce?
NO YES
Measure D.H.W.
temperature. Is
it between 57
o
and 63 C?
NO YES
Modulation
O.K.
YES
Set selector switch
to"on".
Turn off D.H.W. flow.
Does main burner
extinguish?
NO
YES
NO
Does fan and pump
continue to run for
approx. 30 seconds?
YES
Turn on roomstat or
external CH control.
Does main burner
relight?
YES
With heating system
With heating system
starting from cold. Is
starting from cold. Is
burner pressure
burner pressure
NO
constant at approx:
constant at approx:
S.I.T. 8.8mbar?
S.I.T. 8.8mbar?
Honeywell 9.0mbar?
Honeywell 9.0mbar?
YES
As heating system
becomes satisfied.
Does burner pressure
reduce?
NO
NO
Isolate supply. Remove block 4 from P.C.B. As boiler
YES
cools does resistance across 'CH thermistor' pins
on block 4 increase from approx 2.5K to 10K Ω?
YES
Is there continuity across
terminals on modulator?
NO
Check continuity from
P.C.B. to modulator.
Rectify if necessary.
Continued
YES
Restore supply. Is there
YES
24V AC across 'main
solenoid' pins on block
1 on P.C.B?
NO
Isolate supply.
Disconnect block 4 from
P.C.B. With D.H.W. rate
of at least 3.7 litres/
minute. Is there
continuity across 'flow- YES
switch' pins on block 4.
NO
Is there continuity
between P.C.B. and
flowswitch in line
connectors ?
YES NO
Rectify as necessary.
Isolate supply.
Disconnect block 4
from P.C.B. Is there
continuity across
'flowswitch' pins on
block 4?
NO
Does pump operate.
NO
Refer to fault finding
Dia. 3.8.
Measure CH flow
temperature. As
heating system
becomes satisfied
YES
is CH flow
temperature
between 78 and
o
82 C
37
Is there 24V AC across
YES
terminals on main
solenoid on gas valve?
NO
Faulty gas valve,
replace.
Isolate supply. Is there continuity
across 'D.H.W. cut out stat' pins
on block 1on P.C.B?
YES NO
Faulty D.H.W. cut
out stat. Replace.
Remove block 1 from P.C.B. Is
there continuity across
secondary pins 1&2 on transformer.
YES NO
Faulty transformer, replace.
Check continuity of cable between
P.C.B., transformer, gas valve &
pressure switch. Rectify if necessary.
Faulty P.C.B., replace.
Faulty flowswitch,
replace
YES
Ensure that all external
CH controls are not
NO calling for heat. Rectify
if necessary.
YES
Faulty P.C.B. , replace.
NO
With D.H.W. demand
of at least 3.7
litres/minute, is there
YES NO
D.H.W. priority?
Does pump continue to
run for a short period?
YES
Boiler working correctly.
Diagram 3.7 continued
NO
221469B