Bosch 14/19CBI - Manual (Page 35)

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19. Fault Finding
NOTE: This fault finding information is for guidance only. Worcester, Bosch Group cannot be held responsible for costs incurred by
persons not deemed to be competent.
The electronic control for this boiler incorporates three lights: Boiler demand, flame on and lockout.
These form the basis for this fault finding guide.
To use this guide, select box below which represents the light situation during your fault, then refer to the appropriate section.
This guide assumes a component failure has occured following a period of normal running. It is not intended to solve installation errors.
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.
WARNING: In addition to the controls, the overheat thermostat and fan are connected directly to the permanent live supply. Under
all circumstances remove the permanent live supply before touching these parts.
WITH A SYSTEM BOILER DEMAND AND USER CONTROL SET TO MAXIMUM:
LIGHT SITUATION DURING FAULT
NO LIGHTS AT ALL FAULT POINT A
FAULT POINT B DEMAND LIGHT ONLY
FAULT POINT C BURNER LIGHT ONLY
ON OR OFF OFF
LOCKOUT LIGHT ON
CONSTANTLY
ON OR OFF OFF
LOCKOUT LIGHT
FLASHING
FAULT POINT D
FAULT POINT E
OTHER FAULTS NOT COVERED BY ABOVE FAULT POINT F