Fault Finding - Bosch Worcester 15SBi Installation And Servicing Instructions

18. 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.
To use this guide, operate the boiler and follow the observations down the left hand column until the boiler fails. The associated tests
will help find the fault.
This guide assumes a component failure has occured following a period of normal runing. 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.
FACIA INDICATOR TEST
Switch on the mains
electrical supply.
Is the facia
indicator
illuminated?
Yes
Refer to
BOILER DEMAND TEST
No
No
Is there mains
230V
at connector X1?
Yes
No
Has fuse F1 blown?
Yes
Replace fuse and
investigate cause.
Suggestions: Cable
damage, connections to (or
faults within) pump, fan,
external system controls.
31
Check electrical
supply to boiler
Replace control board
(Section 15.4.9)