28
2000225231B
Diagram 9.2
9 Fault Finding
Is neon 1 lit?
Is neon 2 lit?
Correct power supply problem.
Is there 230V~
between 3 on thermostat and N ?
Replace thermostat.
Is neon 3 lit?
Is there 230V~ between
"N/C" on air pressure switch and N ?
Check yellow cable between printed circuit
board and air pressure switch.
If satisfactory replace printed circuit board.
Is there 230V~ between "C" on air
pressure switch and N ?
Replace air pressure switch.
Does fan run?
Replace fan.
Replace printed circuit board.
Does fan Hunt?
Inspect air tubes for leaks, kinks and correct
fitting. If satisfactory replace faulty air pressure
switch.
Is there 230V~between "N/O" on air
pressure switch and N ?
Isolate supply, test harness continuity.
If satisfactory replace printed circiut board.
Is there 230V~ between pilot
multi-functional control solenoid
blue and brown connections?
Check lead continuity and inspect electrode and
lead for damage.
Is there a spark at pilot burner?
Check for pilot jet blockage, incorrect electrode
adjustment. If satisfactory replace
multi-functional control.
Does pilot light?
Inspect electrode lead /connection
for poor contact. Check electrical supply
polarity and correct if necessary.
If satisfactory replace printed circuit board.
With pilot lit does spark stop?
Isolate supply, test harness and replace as required.
Is there 230V~ between main
multi-functional control solenoid black
and blue cables?
YES
Replace multi-functional control.
Is Neon 4 lit?
Does main burner light?
System satisfactory
Is there 230V~ between SL and
N and between L and N ?
Is there 230V~ between yellow connection
on overheat device and N ?
Is there 230V~ between motor connections on fan?
Isolate electrical supply test fan
harness continuity.
If satisfactory replace printed circuit board.
For gravity domestic hot water systems only,
check continuity of yellow link. For fully
pumped systems, check overheat reset.
If satisfactory replace overheat device.
Before detailed checking of electrical components ensure that remote controls are calling for heat. Check the gas supply is free of obstructions and purged of
air. Check the overheat cutoff has not operated, for fully pumped systems only. Isolate the electrical supply and physically check ALL cables, connections
and the printed circuit board fuse. Check the air tubes to the air pressure switch. Switch on the electrical supply and check for correct polarity. Turn the
boiler thermostat to its maximum setting. Also check fuses.
YES
YES
YES
YES
YES
NO
NO
NO
NO
NO
NO
NO
NO
YES
NO
YES
YES
YES
YES
YES
NO
NO
YES
NO
YES
YES
YES
YES
YES
NO
NO
NO
NO
NO
NO
YES
NO
M A I N T E R M I N A L S T R I P
C O N T R O L T H E R M O S T A T
