What to check if the burner flame is slow to stabilise during start up?

If an oil boiler is working but the flame in the burner is slow to stabilise during the start up, a heating engineer can check the following. Please note, it is important to always isolate the electricity supply to the boiler before working on the boiler.

• Check if there is insufficient air supply - check the air damper setting and the condition of the fan.
• Check that the room ventilation is adequate - please refer to the boiler Manual for further support here.
• Check the nozzle size and type.
• Check whether the fuel pressure may be too low - check and adjust as required. 
• Check whether there is insufficient draught - clean boiler heat exchanger and check condition of flue.