Fault Finding - Worcester Highflow 400 RSF Installation And Servicing Instructions

17. Fault Finding

Note: 1. All voltage measurements are with respect to neutral unless otherwise stated. 2. Before changing any component indicated in the chart, it is essential that
the associated wiring is checked for continuity, condition and correct routing. 3. Preliminary electrical system checks are the first electrical checks to be carried out
during a fault finding procedure. On completion of the Service/Fault Finding task which has required the breaking and remaking of electrical connections, check –
(a) EARTH CONTINUITY, (b) SHORT CIRCUIT CHECK, (c) POLARITY and (d) RESISTANCE TO EARTH.
Switch on the mains
electrical supply. Is the
Standby Indicator
illuminated?
Refer to Section:
FAILURE AT POINT A
or
FAILURE AT POINT J
Set the operating
switch (or
programmer) to
WATER and turn the
hot water control stat
to maximum, but
keep the heating
control stat to off.
Does the pump run?
POINT
NO
Is there 230V at X11
Is there 230V at the
top end of the fuse?
YES
Is there 230V at pin 1 of
Replace the Standby
NO
Is there 230V at
pin 3 of terminal
Is there 230V at
(Right pink wire).
Is there 230V at
pin 1 of terminal
YES
B
This Fault Finding Chart is to be used in conjunction with the Operational Flow
Diagrams in Section 16. To find the fault, locate the point on the flow diagram at
which the appliance has failed, e.g. letter B. Then read the corresponding section
in the fault finding chart, e.g. Failure at point B. Note: Each section assumes
that the appliance operates correctly up to that point.
NO
Check the mains electrical supply and
pin 4? (L)
YES
NO
YES
NO
terminal X14?
(Left red wire).
YES
Indicator.
START OF DOMESTIC HOT WATER TEST
NO
X12?
(D.H.W.).
YES
NO
pin 3 of
terminal X2?
YES
X10?
(Brown wire).
YES
Replace the
pump
50
external wiring.
Fuse has blown. Check condition of cables and all
internal and external electrical components. Repair
fault and replace fuse.
Heatbank Overheat Stat has
tripped. Investigate
reason/reset stat.
NO
Is there 230V at
pin 2 of terminal
X12?
(L).
YES
Replace the operating switch
(or programmer)
NO
Is there 230V at
pin 1 of
terminal X2?
(Left pink wire).
YES
Replace the hot water
control thermostat.
Replace the
control board
Replace the
control board
Replace the
control board