Technical data

54
Is there 230V at
pin 3 of
terminal X7?
(Brown wire)
Replace the
diverter valve
Replace the
control board
Does the fan run and an
automatic ignition
sequence occur,
ending in full
burner ignition?
Does the burner operate
at or near minimum
gas pressure?
Does the diverter
valve operate?
NOTE: This failure
would cause cold
water at the flow
outlet and the boiler
will cycle on the
heating control stat
END OF
CENTRAL HEATING
TEST
Replace the
gas valve
Is there 230V at pin 3
of terminal X15?
(Right white wire)
NO
Is there 230V at pin 2
of terminal X15?
(Left white wire)
Replace the
control board
Replace the
control board
Replace the
heating control stat.
NO NO
NO
NO NO
YES
YES YES
FAILURE AT
POINT L
FAILURE AT POINT M
FAILURE AT POINT N
YES
YES
YES
Is there 230V at
pin 4 of
terminal X12?
(C.H.)
Replace the
operating switch
(or programmer)
Replace the
control board
Replace the
control board
Replace room thermostat
or insert optional link
Set the operating switch
(or programmer)
to HEATING and WATER
and turn the heating
control stat and room
thermostat (if fitted) to
maximum (but keep the
hot water control stat
in the OFF position).
Does the DEMAND
lamp illuminate?
Before tests ensure
pump has stopped
Is there 230V at
pin 2 of
terminal X13?
(Right roomstat
terminal)
Is there 230V at
pin 3 of
terminal X13?
(Left roomstat
terminal)
Is there approx. 90V
at pin 5 of terminal
X3? (DEM).
Note: Lamp is not
supplied directly by
mains voltage
Replace demand
indicator
Replace the
control board
Does the pump run?
NO
NO
NO
NO
NO
NO
YES
YES
YES
YES
YES
YES
FAILURE AT POINT J
FAILURE
AT POINT K
START OF CENTRAL HEATING TEST