by matt walker » Sun Oct 13, 2013 5:54 pm
Carter, no worries on the message, I wasn't bothered. Just wasn't sure it went through. Glad to hear you got it, and glad to have you here.
As for the riser, I would take a lot of that stuff with a grain of salt, personally. Even folks with tons of experience would be hard pressed to be able to discern the small differences in performance gains once we are in the ball park of a well running stove. That includes me and everyone else. Without very expensive test equipment, it's all just guessing.
So, with that said, let the guessing commence! I have read, from a source with said test equipment, PvdB, that what we actually want in that part of the stove is a smooth flow. General consensus is that round is slightly better in this regard, but keep in mind that with a square section core, the "vortex" is actually a horizontal rotor spinning in the low pressure area made at the corner where the top of the burn tunnel transitions sharply into the riser. So, there's a rotor there, rolling along inside the base of the riser. In that way a square riser can hold that turbulence format just fine. I guess I'm saying I doubt it matters a whole heck of a lot if you've got proper sizing and insulating materials everywhere. At that point the gains are a matter of small percentages and, like I said, we'd be hard pressed to sense any significant difference.
I like round because it's easy to cast that shape using highly insulated materials. I would guess that they prefer square for the same reason, it's easy to build with their chosen material which is brick. I will say that I think heavy firebrick is exactly wrong for everything in the burn zone, core and riser included. That's my opinion, but I've verified enough times to be confident that I prefer an insulated build at the expense of a little less durability.