Firebird boiler has riello burner ,When you call for heating or hot water fan motor runs but burner can take up to ten minutes to ignite is this correct operration.
You Don't say whether its a Riello R40, or the newer RDB, but the cause is usually the same, Repalce the Photo resistor, this in 90% of cases is the cause of a long pre purge on a Riello burner
