Saunier Duval Xeon 40ff Instructions For Use Installation And Servicing page 28

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
NO
Is neon 1 lit?
YES
NO
Is neon 2 lit?
YES
Is neon 3 lit?
YES
Is Neon 4 lit?
NO
YES
YES
Does main burner light?
YES
System satisfactory
221657C
9 Fault Finding
boiler thermostat to its maximum setting. Also check fuses.
Is there 230V~ between SL and
N and between L
Is there 230V~ between yellow connection
on overheat device and N ?
YES
Is there 230V~
between 3 on thermostat and N ?
NO
Is there 230V~ between
"N/C" on air pressure switch and N ?
YES
Is there 230V~ between "C" on air
pressure switch and N ?
Does fan run?
YES
Does fan Hunt?
NO
YES
Is there 230V~between "N/O" on air
pressure switch and N ?
Is there 230V~ between pilot
multi-functional control solenoid
blue and brown connections?
YES
Is there a spark at pilot burner?
YES
Does pilot light?
YES
With pilot lit does spark stop?
NO
Is there 230V~ between main
multi-functional control solenoid black
and blue cables?
YES
Replace multi-functional control.
NO
and N ?
YES
NO
YES
NO
NO
NO
YES
NO
Replace fan.
YES
NO
NO
NO
NO
NO
NO
28
Correct power supply problem.
For gravity domestic hot water systems only,
check continuity of yellow link. For fully
pumped systems, check overheat reset.
If satisfactory replace overheat device.
Replace thermostat.
Check yellow cable between printed circuit
board and air pressure switch.
If satisfactory replace printed circuit board.
Replace air pressure switch.
Is there 230V~ between motor connections on fan?
YES
Isolate electrical supply test fan
harness continuity.
If satisfactory replace printed circuit board.
Replace printed circuit board.
Inspect air tubes for leaks, kinks and correct
fitting. If satisfactory replace faulty air pressure
switch.
Isolate supply, test harness continuity.
If satisfactory replace printed circiut board.
Check lead continuity and inspect electrode and
lead for damage.
Check for pilot jet blockage, incorrect electrode
adjustment. If satisfactory replace
multi-functional control.
Inspect electrode lead /connection
for poor contact. Check electrical supply
polarity and correct if necessary.
If satisfactory replace printed circuit board.
Isolate supply, test harness and replace as required.
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
NO
Diagram 9.2