Worcester 24CDi Installation And Servicing Instructions

35
Remove front panel.
Reset and restart the
boiler. Can a flame be
seen through the spy
glass?
Turn off boiler. Remove
inner cover and
combustion chamber
cover. Is the sense
electrode and lead in
good condition and is
gap correct.
Remove multiway
connector from board
position
ST16.
Is there continuity
from contact
11 (white
wire) to flame sensor?
Does the flashing fault
signal occur at the
start of a demand?
Replace control board (Section 16.4.23).
Note: It is not possible to reliably check
the cross-light performance of the burner.
In the unlikely event of such a fault,
investigate flue problems or replace
burner or injector. (Section 16.4.7/8).
Flashing occurs at end
of demand. Replace
gas valve.
(Section 16.4.11).
Remove inner cover.
Reset and restart the
boiler. Does a spark
occur across the
electrodes?
Turn off boiler. Remove
the multiway
connector from board
position ST16. Test
resistance across
contacts 7 and 8
(brown wires) and 9
and 10 (violet wires).
Are both reading
below 100 ohms?
Replace control board.
(Section 16.4.23).
If problem not solved
replace gas valve.
(Section 15.4.11)
Repair or replace flame
sensor
(Section 16.4.10)
or wiring.
Replace gas valve.
(Section 16.4.11).
Are the electrodes and
gap and connections
in good order?
Replace control board.
(Section 16.4.23).
Remove both brown
connectors from gas
valve.
(First remove pressure
switch bracket).
Is there continuity
from brown and violet
wires to multiway
connector?
Repair or replace
harness.
Repair or replace
spark electrode
(Section 16.4.9)
or HT leads
Is the gas supply
connected and at the
correct inlet and
outlet pressures?
Rectify gas supply
problem.
FAIL POINT H “Burner Lockout”
No
No No
No
No
No
No
No
No
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes

Worcester 24CDi Specifications

General

Model	24CDi
Output	24 kW
Efficiency Rating	A
Max Working Pressure	3 bar
Central Heating Flow Temperature Range	30 - 80 °C
Fuel Type	Natural Gas
Mounting	Wall Mounted