Alpha CD24C Installation And Servicing Instructions page 36

10.5 FAULT FINDING SOLUTIONS F to K
F
Check and correct:-
1. Ignition electrodes and leads
2. Electrode connections
3. Spark gap and position
4. Connections at ignition generator and PCB connector X7
Is spark generator (T2)
making a clicking noise
G
Check and correct:-
1. Check polarity of electrical supply
2. Flame sensing electrode and lead connections
3. Electrode position
4. Blockage of pressure tubes
H
Allow to cool.
Continuity across
thermostat terminals
YES
Air in main heat exchanger,
blocked heat exchanger/pipework
or pump not circulating water
I
240V at internal clock
terminals 1 and 2
YES
Continuity across
clock terminals 3 and 4
NO
Internal clock calling
for heat
J
Continuity across primary
pressure switch terminals
NO
K
Continuity across DHW
switch at inline connector
NO
Diverter valve
spindle operating
NO
DHW flow valve
diaphragm damaged
NO
Diverter valve
spindle assy. fault
Alpha CD24C/32C - Fault Finding
36
YES
NO
NO
Replace overheat thermostat
YES
Vent air, clear blockage
NO 240V at PCB - X1 connector,
terminals 55 and N
YES
Wiring between clock
and PCB is correct
YES
Replace clock
36 V DC at PCB across
YES
X9 connector terminal 45
and X8 connector terminal 46
36 V DC between
YES
PCB - X8 connector,
terminals 46, 47
YES
Replace DHW switch
YES
Replace diaphragm
YES
Replace diverter valve
PCB, X7 connector is 200V ac
across terminals 22, 23 during ignition
NO
YES
Replace PCB
YES
YES
NO
Replace primary pressure switch
NO
YES
Replace pump
Wiring between clock
and PCB is correct
YES
240V at PCB - X1 connector,
terminals 34 and N
Check external controls
are calling for heat
Replace PCB
Replace PCB
Replace ignition
generator
Replace PCB
NO