An excellent summary by my good friend!
Whilst it is possible to make your own burner and achieve a reasonable result from plans on the internet please do so with extreme caution. Burners of all types can get too hot, if they are not made accurately there is a very good chance that the flame will move from the outside ofthe burner to the inside, it will then get so hot that the silver solder and copper will melt, you then have a boat on fire! I make two types of burner, one from all brass which burns quite fierce and is suitable for certain flues, up to 2.5" / 63mm diameter and the other is ceramic which is suited to twin flue boilers. The two require a completely different design in order to opperate safely and reliably, especially so for the ceramic type. There are lots of suppliers of ceramic material for burners but be aware that 99% will soon burn through into the gas chamber and the burner is quickly destroyed and a serious fire may occur. The critical factors on my burners are the distance between jet and venturi, the diameter of the inlet tube, the diameter of the venturi, the size and positioning of the air inlet holes, the depth and diameter of the burner venturi, the positioning of the grid plate and the design of the gas mix chamber. Gas speed past the air holes has to be correct and then it has to be slowed down once inside the burner in order to obtain an even distribution of gas. At lower gas pressures this is not a problem but if a fierce, hot flame is required then it quickly becomes apparant that the burn is not even. The blue flame cones should not come into contact with the grid and for the hottest burn should be about 5mm high, enabling the burner to work in very close proximity to the first flue tube. One other indication of an incorrect burner is if flames come out of the chimney - you cant easily see this so test at night with the lights off. One factor not mentioned so far is the very real danger posed by Carbon Monoxide poisening. These burners put out high levels of CO when made well, a poor burner puts out an incredibly high CO level and if fired indoors can quickly become very dangerous or even fatal. If you light your burners indoors please have very good ventilation! I have two digital CO monitors in my workshop! Be safe and enjoy youseives.