Potterton Derwent Compact Plus Installation, Operation & Maintenance Manual page 24

SECTION 5
PAGE 22
Fault Finding
Stage 1
Boiler does not attempt
to light.
Control box does not
lockout.
Stage 2
Boiler does not attempt
to light even with the fan
running
Stage 3
No ignition spark.
Pilot does not light.
Control box goes to
lockout.
Stage 4
Ignition sparks.
Pilot burner does not
light.
Control box locks out.
Stage 5
Pilot burner lights.
Control box goes to
lockout after 10 seconds.
INSTALLATION, OPERATION AND MAINTENANCE MANUAL
a) Check electricity supply is available to boiler and mains LED is illuminated.
b) Check the boiler is being called to operate.
c) Check overheat cut off device has not operated.
d) Check power supply is available to control box (see wiring diagram). Replace box if
faulty.
e) Check burner overheat cut-off has not operated
f) Check secondary heat-exchanger overheat cut-off has not operated
g) Check gas supply
a) Check the air pressure switch for low load
b) Check that the air pressure switch tube is not blocked
c) Check the integrity of the differential air pressure switch after the fan
d) Check the cleaning of the secondary and primary heat-exchangers
e) Check the damper position
f) Check the rheostat position
a) Check ignition electrode continuity for earth fault, check the ignition wire.
b) Check power supply is available to electronic ignitor during ignition period
c) Check operation of ignitor. Replace if necessary.
a) Check gas supply is available at the pilot burner at the correct pressure.
b) Check gas supply is purged of air.
c) Check pilot injector.
d) Check ignition electrode position.
a) Check electrical supply polarity.
b) Check earth continuity to pilot burner.
c) Check pilot burner pressure is correct.
d) Check there is no earth leakage on ionisation probe circuit.
e) Check ionisation probe circuit for correct flame current. This is achieved by
connecting a DC micro ammeter in series. A reading of at least 3 to 4µA DC should
be obtained. If this is obtained and the control box continues to lock out then replace
the control box.
POTTERTON COMMERCIAL PRODUCTS DIVISION
DERWENT COMPACT PLUS - CONDENSING