Technical information

Combi 70 & Combi 90 Oil Boilers
52
11 - FAULT FINDING
Flue is blocked.
Insufficient flue draught.
Flue pipe or liner is too large or existing stack is unlined.
Insufficient combustion air supply to burner.
Insufficient combustion air supply to burner.
Incorrect or faulty nozzle fitted.
Fuel pressure too low.
Combustion air pipe being heated by flue pipe (balanced flue).
Oil leak in supply line or burner.
Leak around boiler cleaning door.
Burner not correctly fitted on mounting flange.
Leakage around flue connection.
Faulty boiler thermostat.
Check flue is clean and unobstructed.
Check flue draught and improve flue as necessary.
Check flue condition/size and alter as necessary.
Check as for high smoke number (above).
Check that a kitchen fan is not drawing products from burner.
Check air damper setting on burner.
Check condition of burner fan.
Check flue terminal is clear (balanced flue).
Check room ventilation is adequate (conventional flue).
Check nozzle size and type and replace if necessary.
Check fuel pressure and adjust as necessary.
Ensure insulation is inserted between flue elbow and air pipe.
Check all joints for leaks and rectify as necessary.
Check, re-tighten nuts or replace gasket as necessary.
Remove and re-fit burner ensuring correct fitting.
Check and re-seal flue as necessary.
Check and replace as necessary.
FAULT
POSSIBLE CAUSE
ACTION
Fumes and puffing on starting
(Conventional flue)
Overheat thermostat operating
Combustion fume smells
Oil smells
Flame slow to stabilise on starting
Boiler faults on central heating and hot water - continued
11.3