Worcester 28Si Installation And Servicing Instructions page 39

The gas valve mode
switch (concealed by
the facia side panel)
is not set correctly
Light indication
during fault not
covered by above
details.
Hot water
temperature always
too hot during a
demand (not
regulating).
Water temperature
very low/low gas
pressure (with all
knobs set to
maximum)?
Turn to 'NORM'
position
Control board is likely
to be wet or damaged
or malfunctioning.
Check for wet board or
connections. Dry and
re-use or replace
control board. (Section
15.4.10).
Hot water sensor
could be off or poorly
fixed to pipe.
Repair or replace
sensor.
(Section 15.4.15).
No
Is the gas set to correct
pressure?
Yes
Remove multiway
connector from board
No
position ST16. Is the
resistance across
contacts 1 and 2
(blue wires) below
60 ohms.
Yes
Replace control board.
(Section 15.4.10).
39
Set pressure.
Remove blue (top)
connector from gas
No
valve.
Is there continuity
along blue wires to
multiway connector?
Yes
Replace gas valve.
(Section 15.4.1).
Repair wires or replace
harness.