Technical information

51
Combi 70 & Combi 90 Oil Boilers
11 - FAULT FINDING
Boiler will not start
No fuel supply
Isolating valve(s) in fuel supply line closed.
Fire valve closed.
Fuel line filter is blocked.
Oil supply line is air locked.
Oil tank empty.
No electrical supply to burner
No electrical supply to boiler.
Controls are not switched on and calling for heat.
Overheat thermostat has tripped.
Boiler thermostat and/or overheat thermostat faulty.
Fault with burner.
Excessive combustion air.
Fault with burner.
Insufficient combustion air supply to burner.
Incorrect or faulty nozzle fitted.
Fuel pressure too high.
Combustion air pipe being heated by flue pipe (balanced flue).
Insufficient combustion air supply to burner.
Contaminated combustion air (balanced flue).
Insufficient oil flow to burner due to restriction in supply line.
Excessive combustion air.
Open and check for adequate supply at burner.
Check and reset as necessary.
Check and clean as necessary.
Vent oil supply line at pump.
Check sight gauge on tank and refill as necessary.
Check for 240 V at boiler terminal block.
Check On/Off switch is set to 'ON'.
Set boiler thermostat to maximum.
Set 3-position switch to 'Heating Constant'.
Check and reset thermostat as necessary.
Check continuity of thermostats and replace as necessary.
Press reset button.
Refer to burner fault finding flow chart.
Reset burner air inlet damper and check combustion.
Refer to burner fault finding flow chart.
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 as for high smoke number (above).
Check flue deflector is correctly fitted to terminal.
Check flue blanking plate is correctly fitted to terminal.
Check position of flue terminal.
Fit vacuum gauge to pump and check pump vacuum.
Check for blockage in filter, valve or pipe and rectify.
Reset burner air inlet damper and check combustion.
FAULT
POSSIBLE CAUSE
ACTION
Burner lights but goes to lock-out
Burner not lighting
Oil & electricity present at burner
Burner fires but smoke visible
from flue or high smoke number
Burner pulsates
Burner cycles On and Off
Boiler faults on central heating and hot water
11.3