Technical data

32
10.3 DOMESTIC HOT WATER - Follow operational sequence
(DHW storage at ambient temperature i.e. cold)
Turn thermostat to max.
neon illuminated
YES
NO
Turn selector to
neon illuminated
YES
NO
Go to section ' ', page 33
A
Replace neon PCB
Replace main PCB
Pump runs, i.e. primary water
to DHW store heat exchanger
PCB - M1 connector,
is 2V DC across
terminals 49, 52
YES
NO
NO
YES
Go to section ' ', page 33
B
Differential flow switch
operated
NO
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C
YES
Fan runs at max. speed
NO
YES
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D
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J
YES
neon
illuminated
Press white reset
button, if neon
stays illuminated
Air pressure switch proved
neon stays off
neon
illuminated
YES
NO
Go to section ' ', page 33
E
Burner output modulates
after approx. 3 mins from max.
until storage temp. set by
DHW stat. is reached
NO
YES
neon off
YES
Burner goes out
YES
Fan stops
YES
Pump continues to run
for 3 minutes
Operation sequence successful
YES
Go to section ' ', page 34
G
DHW tap is opened
When storage temperature
decreases to that set by
the DHW thermostat
neon illuminates
Spark at ignition electrodes
for upto 10 seconds
YES
NO
YES
YES
Press red button to reset
NO
YES
Burner lights
YES
Go to section ' ', page 33
F
Go to section ' ', page 34
I
Go to section ' ', page 34
H
Red reset button
illuminated
But, burner does not stay
alight after 10 seconds
If still illuminated,
Go to section ' ', page 34
K
Alpha 500E - Fault Finding