Worcester 26CDi XTRA Installation And Servicing Instructions page 41

With CH control knob
fully clockwise, does
No
the boiler ignite and
appear to run
normally in central
heating mode?
Yes
Red diode is
damaged. Replace
control board.
(Section 14.3.23)
With a hot water tap
fully open, does the
No
boiler ignite and
appear to run
normally in hot water
mode?
Yes
Red diode is
damaged. Replace
control board.
(Section 14.3.23)
No
Is there 230V AC
across terminal ST8
pins LR and N?
Yes
No
Is there a link at
terminal ST13 pins 1
and 2?
Yes
Is there an electronic
No
programmer at
position ST5 at right-
hand end of board?
Yes
Remove programmer
No
connector from board
edge. Does CH lamp
now light?
Yes
Correctly set or
replace electronic
programmer.
Remove multiway
connector from board
No
position ST16. With
tap still open is there
continuity across
contacts 19 and 20
(2 pink wires)?
Yes
Replace control board.
(Section 14.3.23).
41
There is no heat
demand. Check room
thermostat or mains
programmer (or link).
Insert or tighten link
Replace control board.
(Section 14.3.23).
Remove the black cover
from the microswitch
No
assembly. With the tap
still open is there
continuity between the
two terminals
(C and NO)?
Yes
Repair or replace
wiring/harness
Visually observe if the
plunger on the diverter
valve assembly is pushing
the microswitch button
(Note: May be helpful if the
tap is repeatedly turned
on and off). If plunger
moves replace
microswitch (Section
14.3.18). If the plunger
does not move replace
water diverting valve.
(Section 14.3.19).