Worcester 24ijunior

40
Remove multiway
connector from board
position ST16. Test
resistance across pins
16 and 17 ( yellow
wire). Is it between 1
kOhm and 30 kOhm?
Test resistance across
contacts 12 and 13
(red wire). Is it
between 1 kOhm and
30 kOhm?
Is there continuity
from individual pins
16 and 17 to DHW
sensor?
Check or replace
DHW sensor.
Is there continuity
from individual
contacts 12 and 13 to
CH sensor?
Repair or replace
harness.
Repair or replace
harness.
Is the multiway
connector at board
position ST16 pushed
fully home on to the
board?
Push fully home
No
No
No
No
No
Yes
Yes
Yes
Check the DHW
sensor. Is it correctly
fitted onto the pipe
with heat conductive
paste between the
pipe and sensor?
Yes
No
Re-fix sensor onto pipe
TEST E
Check or replace
CH sensor.
Test resistance across
contacts 14 and 15
(green wire).
Is it open circuit?
Turn off electrical
supply.
Remove fan connector
from board position
ST1.
Test resistance across
contacts to black &
white cables.
Is it between 75 and
175 ohms?
Check/repair fan
harness or repalce fan.
Air pressure switch
is shorting.
Check tubes for
blockage or replace
switch.
No
No
Yes
Yes
Yes
Test resistance across
contacts to black &
red cables. Is it
between 30 and 90
ohms?
Yes
Yes
No