37
Has fuse F1 blown?
Likely to be caused by
mains 230V parts external
to the control board, e.g
cable damage, connections
to (or faults within) pump,
fan (RSF only), gas valve /
ignitor or external 230V
controls. Replace fuse F1
and check all 230V parts or
replace control board.
FA
IL POINT A
No
Yes
Yes
No
Is there 230Vac
across connector X2
terminals CH and N?
Set CH temperature
control fully
clockwise and all external
CH settings to maximum.
Is there 230Vac across
connector X3 terminals
R
R
and N?
Replace control board.
FA
IL POINT C
No
Yes
Yes
Green diode only is faulty.
Control board will still operate
corrctly. Replace control board
if green light is required.
FAIL POINT B
Check electrical
supply to boiler.
I
s there a 230Vac
live supply across
connector X1 pins
L&N?
Has fuse F2 blown?
No
Transformer likely to
be faulty. Replace
control board.
Likely to be caused by
internal fault on control
board, but it could be
caused by low voltage
wiring (e.g. wiring
shorts or terminals
touching boiler
chassis). Replace fuse
F2 and check wiring or
replace control board.
Yes
Correctly set or
replace CH
programmer or link
terminals L to CH.
No
Correctly set or replace room
thermostat or link terminals Rs to
R
R
on connector X3
Turbine may be
sticking.
Replace flow turbine.
FA
IL POINT D
No
Yes
Yes
No
Is there a 230Vac live
supply across
connector X2
terminals
DHW and N?
Replace control board.
Locate but do not
disconnect the 3 pole in-
line connector to the
turbine, With the tap still
open, is there 5Vdc across
the white and black wires
/ terminals (put probes
inside the connector
housing)?
Yes
Correctly set or
replace DHW
programmer or link
terminals L to DHW.
Set HW temperature
control fully clockwise and
a hot water tap fully open.
Boiler should ignite when
flow rate is approximately
3L/min.
Does boiler ignite at much
higher flow rates?
No
Replace control
board. It is wise to
also replace the
turbine in case this
was the cause of the
board failure.
Is there between 1.5
and 4.5Vdc across
the green and black
wires / terminals?
Yes
No
Replace turbine.
Summary of Contents for Highflow 400 BF
Page 43: ...43 ...