Alpha CD12S - Fault Finding

37
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
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
Alpha CD12S/20S/28S - Fault Finding
Turn thermostat to max.
External controls
not calling for heat
If fitted, internal
clock calling for heat
240 V across main
terminal block,
terminals 1 and N
YES
YES
NO
Turn selector to position 2 (ON)
Go to section ' ', page 34A
YES
YES
(BUT)
Pump runs and
fan runs
Go to section ' ', page 35I
YES
Go to section ' ', page 34D
Burner output modulates until
set temperature is reached
Burner goes out
NO
YES
Operation sequence successful
Pump continues to run until temperature
reduces to set temperature
YES
Go to section ' ', page 34D
Fan stops after 50 seconds
Check gas valve adjustment
CH system pressure
too low. Re-pressurise
to 1.0 bar
Primary
temperature sensor
faulty
NO
NO
Go to section ' ', page 35J
Neon A and B
flashing alternately
Neon B illuminated cont.
Neon A flashing
Neon A and B
flashing at the same time
Neon A flashing
Go to section ' ', page 34C
YES
YES
YES
YES
YES
Fan or
flue fault
Neon B illuminated
continuously
YES
(BUT)
Go to section ' ', page 35G
Burner does not stay
alight after 10 seconds
Spark at ignition electrodes
for upto 10 seconds
YES
Burner lights
Neon C illuminated
YES
YES
NO
Reset by rotating
selector switch
Reset by rotating
selector switch
Overheat thermostat
or thermal fuse
has operated
Neon B illuminated
continuously
YES
Reset by rotating
selector switch
Neon B illuminated
continuously
Neon B flashing
NO
YES
If still no spark
Go to section ' ', page 35F
Go to section ' ', page 35E
If still illuminated,
Go to section ' ', page 35H
Neon D illuminated continuously
Pump fault or primary
flow restricted
Go to section ' ', page 34B