Hi, This thread might be interesting as I'm not quite sure how it will turn out! A Danish member of an another forum that I belong to bought a boiler which didn't have a burner. He had tried using a blowlamp type burner with no success other than melting some solder on a chimney joint. The boiler is copper hard soldered together 100mm long, 55mm in diameter with a 15mm ID flue which protrudes 15 mm out of the boiler which looks as if it could be professionally made. The flue has no cross tubes. I have made quite a lot of boilers and burners some of which have been quite small. If I had designed this boiler I would have used a larger 22mm flue. However someone made this boiler which might have produced steam well. So I got a bit interested as the smaller flue would allow quite a lot of usable water in the boiler, with of course a much smaller heating area. As I mostly make working steam models i.e. locomotives that run on rails and boats that are used on water a longer running time has a lot going for it. So a drawing was made that showed the differnce between the two flue sizes and some sums done to see the difference in boiler volume to heating area. There is quite a difference in this ratio so things didn't look good. But I thought I would give it a go anyway and made a copy boiler. This is very similar being a couple of mm shorter (the longest bit of 55mm tube I had) and the flue is 15mm OD not ID as the original. I'm not sure how long I can work on this so I will do it in short sections. Regards Tony. Original boiler. Comparative drawing. Testing copy boiler.