Fault Finding - Alpha CD25C Installation And Servicing Instructions

10 FAULT FINDING

10.1 CARRY OUT INITIAL FAULT FINDING CHECKS
1. Check that gas, water and electrical supplies are available at the boiler.
i.e. Inlet gas pressure = 20 mbar
Electrical supply = 230/240 V ~ 50 Hz
CH water system pressurised to between 0.75 and 1.25 bar
DHW flow rate is more than 2.5 litre/min
2. Carry out electrical system checks, i.e. Earth Continuity, Resistance to Earth, Short Circuit and Polarity with a suitable meter.
Note: These checks must be repeated after any servicing or fault finding.
3. Ensure all external controls are calling for heat and check all external and internal fuses.
4. Check that the gas and water pipework has been connected to the correct connections on the boiler and all valves are open.
However, before any servicing or replacement of parts ensure the gas and electrical supplies are isolated.
10.2 CENTRAL HEATING - Follow operational sequence
Turn selector to
Neon D illuminated continuously
YES
Turn thermostat to max.
YES
Pump runs and
fan runs
YES
YES
(BUT)
Spark at ignition electrodes
for upto 10 seconds
YES
Burner lights
Neon C illuminated
YES
Burner output modulates until
set temperature is reached
YES
Burner goes out
NO
Go to section '
240 V across main
terminal block,
terminals 1 and N
If fitted, internal
clock calling for heat
Neon B illuminated cont.
NO
Neon A flashing
Neon A and B
flashing alternately
Neon A flashing
Neon A and B
flashing at the same time
NO
Neon B illuminated
continuously
Neon B illuminated
continuously
NO
Neon B flashing
YES
(BUT)
Burner does not stay
alight after 10 seconds
NO
Check gas valve adjustment
YES
Fan stops after 50 seconds
A ', page 35
NO
External controls
not calling for heat
Go to section ' ', page 36
YES
Pump fault or primary
flow restricted
CH system pressure
YES
too low. Re-pressurise
to 1.0 bar
Primary/DHW
YES
temperature sensor
faulty
YES
Fan or
flue fault
YES
Reset by rotating
selector switch
YES
Reset by rotating
selector switch
YES
Overheat thermostat
operated
Neon B illuminated
continuously
YES
Pump continues to run until temperature
Operation sequence successful
Alpha CD25C/28C/35C - Fault Finding
I
Go to section '
Go to section '
Go to section '
Go to section '
If still no spark
Go to section '
Go to section '
If still illuminated,
Go to section '
Reset by rotating
selector switch
Go to section '
Go to section '
reduces to set temperature
YES
B ', page 35
J ', page 36
C ', page 35
D ', page 35
F ', page 36
E ', page 36
H ', page 36
G ', page 36
D ', page 35
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