We have a apollo fanfare and when it first starts up in the morning after a minute it bangs then turns off then it starts again and it is fine all day untill the next morning and then it starts again.We had a new pump fitted and we had the auto bleed radiator valves put on as there was air in the rads there is enough water in the expansion tank and which is open air and the water has been drained and clean water added with fernox the boiler is old but it goes fine all day and we just have the problem on the first ignition all the time. can anyone give us some advice please.