Office of Steam Forum for Model & Toy Steam Gas & Hot Air Engines

Hi Jan,

Is the heat exchangers underneath solid copper rod, like one would use on a porcupine type, or hollow tubes?

Solid 2 mm rods bent into a staple shape.  I had built several boilers using hedgehog/porcupine rods but it was sometimes a bit difficult to stop them moving during soldering, it is quite difficult to turn a should on small diameter copper rods so I came up with the idea of using a staple shape which are sort of sprung into their holes and pushed down onto a spacer which keeps them all the same height; this spacer being removed before soldering.  I don't think that small hollow tubes would have any advantage over solid rods as I think they would soon clog and if the boiler ran dry burner out.  This is only an opinion I haven't tried using tubes except in larger sizes.

Take care.

Tony