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12.1 BOILER FAULT FINDING
Always isolate the electricity supply to the boiler before working on the boiler.
Figure 12-1:
Boiler fault fi nding
Fault
Remedies
Boiler will not start:
No fuel supply.
Ensure that an adequate supply of fuel is available and that the fuel supply valve is
open.
Check the condition of the fuel fi lter, clean if necessary.
Ensure fuel supply is reaching burner and vent pump.
Check that the fi re valve has not operated to shut off the oil supply.
No electricity supply.
Ensure electricity supply to the boiler is switched on and that all controls are calling
for heat.
Ensure that the overheat thermostat has not tripped, reset if necessary.
Check that a mains supply is present at the burner terminal block.
If not, check the boiler and overheat thermostat.
Burner not starting - fuel and electricity supplies present.
Press the reset button on the burner control box if it is lit.
Refer to burner fault fi nding charts.
Burner lights but goes to lock-out.
If the fl ame is unstable, check the combustion settings.
Refer to burner fault fi nding charts.
Boiler works but:
1.
Visible smoke from fl ue or high smoke number.
Insuffi cient air supply - check the air damper setting and the condition of the fan.
Check room ventilation is adequate, see Section 9.1.
Check the nozzle size and type.
Fuel pressure may be too high - check and adjust.
2. Burner
pulses.
Insuffi cient air supply - check the air damper setting and the condition of the fan.
Check room ventilation is adequate, see Section 9.1.
Check the nozzle size and type.
3.
Flame slow to stabilise during start up.
Insuffi cient air supply - check the air damper setting and the condition of the fan.
Check room ventilation is adequate, see Section 9.1.
Check the nozzle size and type.
Fuel pressure may be too low - check and adjust.
Insuffi cient draught - clean boiler heat exchanger and check condition of fl ue.
4.
Water temperature low.
Undersized nozzle and/or low fuel pressure.
Check condition of boiler heat exchanger and clean if necessary.
Check the boiler thermostat.
Check the combustion settings.
Check the condition of the fuel fi lter.
5.
Boiler operating on overheat thermostat.
Faulty boiler thermostat. No circulation, check circulating pump. Check for air lock.
6.
Fumes and puffi ng during starting (conventional fl ue)
Check the condition of the chimney, ensure it is not blocked and is high enough to
produce the required draught. Check that there is an adequate air supply near the
burner and that a kitchen fan is not drawing products out of the burner.
7.
Oil odours.
Check all fuel line connections, remake as necessary.
8.
Combustion fumes smell.
Check boiler cleaning cover and seal are correctly fi tted.
Check burner is correctly fi tted onto correct fl ange.
Check fl ue is correctly sealed into fl ue outlet of boiler.
Check the condensate pipe and trap are operating correctly.
Fault Finding
FAULT FINDING
12
WARNING
Check cleaning door seal, boiler/fl ue seal and
burner fl ange seal with fl ue gas analyser for
a minimum of 60 seconds and a distance of
100mm (from each seal) to ensure there is no
leak of fl ues gases.
