Fault Finding - Worcester 24CDi Installation And Servicing Instructions

19. Fault Finding

Note: This fault-finding information is for guidance only. Worcester Heat Systems cannot be held responsible for costs incurred by
persons not deemed to be competent.
The electronic control system for this boiler incorporates four lights on the facia. These are used to show normal operating status. But as
a secondary function, by flashing, they can also be used to help provide fault diagnostics. Therefore, with individual or groups of lights
being permanently off, on or flashing, every normal fault can be identified.
To use the fault finding system, select a box below which represents the light situation during your fault. Then refer to the appropriate
following section. This fault-finding system assumes that the appliance has been operating correctly until the time of failure.
PRELIMINARY CHECKS
Preliminary electrical system checks are the first electrical checks to be carried out during a fault-finding procedure. On completion of
the Service/Fault-Finding task which has required the breaking and remaking of electrical connections, check (a) EARTH CONTINUITY,
(b) SHORT CIRCUIT CHECK, (c) POLARITY and (d) RESISTANCE TO EARTH.
FAIL POINT C
FAIL POINT D
FAIL POINT F
FAIL POINT G
FAIL POINT H
FAIL POINT I
Note:
Slow flash is once per second, fast flash is five times per second.
Slow flash can only be cleared by using the facia reset button (press for at least one second).
Fast flash is cleared by removing fault and/or main switch off/on.
LIGHT SITUATION DURING FAULT
No green light
No green light
(Red lights work)
(Red lights function)
No light
No red light
(Other lights work)
(other lights function in other modes)
Light on constant
(CH knob in OFF
position)
Flashing slow
Flashing fast
POWER ON CH DEMAND
(Green)
Other faults not covered by above
31
No lights at all
No red lights
No red lights
(Green light working)
(Green light functions)
No red light
No light
(other lights function in other modes) (Other lights work)
2 lights flashing slowly
Flashing fast
HW DEMAND
(Red) (Red)
FAIL POINT A
FAIL POINT B
FAIL POINT E
FAIL POINT J
BURNER ON
(Red)
FAIL POINT K