Worcester Highflow 400 RSF Installation And Servicing Instructions page 53

NO
Set the operating switch
(or programmer)
to OFF, and turn both
control knobs
anti-clockwise to OFF.
Does the pump continue
to run for approx.
5 minutes?
YES
NO
When the pump
has stopped,
turn on fully a
hot water tap.
Does the demand
indicator
illuminate?
YES
NO
Does the pump run?
YES
END OF
DOMESTIC HOT
WATER TEST
Whether the pump
stops immediately
or continues
indefinitely the
control board will
be at fault.
Replace control board
NO
Is there 230V at
pin 1 of
terminal X1?
(Blue wire)
YES
Is there approx. 90V
at pin 5 of terminal
X3? (DEM)
Note: Lamp is not
NO
driven directly by
mains voltage
YES
Replace demand
indicator
Replace the
control board
53
NO
Is there 230V at
pin 3 of
terminal X1?
(Brown wire)
YES
Replace the
flow switch
Replace the
control board
Replace the
control board