Worcester 24ijunior Installation And Servicing Instructions page 40

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