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

I was guessing a boiler flue that swirls the heat/gas but no idea what it's on...

Is it engine related?

Yeah Nick, they squeezed the flue across from each other then again at 90 degree's to the first ones. I don't know if there's a third set farther in.
 They do three things, you got one with swirls the heat but it also creates more surface to heat and increases boiler capacity.