I am about to create a system very similar to what you described. I bought one and will be installing it this week. My situation is as follows.
Our 1st floor fireplace is too big and is extremely in-efficient. The flue is off-set to one side. I intend to remove the flue side half of the fireplace bottom. That section of the floor will be completely removed (and a couple courses of block below that). The wood burner goes directly below that. My flue will go through the center of that 25x30 inch hole and mate with the fireplace flue. Directly in the center of the fireplace (centered height-wise, these units are larger than I first perceived them to be, but nicer than I thought!) is where the unit in question will go.
What I'll actually have is convection pressured preheated air going through the unit. (if I'm smart enough to open the cellar door) The fireplace becomes a huge register with forced and convecion powered heat. (Provided again, I'm smart enough to open the fireplace door). I'm putting a physical devider in the fireplace.
I will construct a reflective surfaced inset for the burner, the fireplace being a register now above it. The burner will be 3 feet from the forced air furnace's heat exchanger. I will probably extend the reflective enclosur to shield it but I do wonder about that free-heated exchanger kicking on the blower at 245 degrees... thats a butt-load of math.
On the other side will be the relocated electric hot water tank. Once the fire temperature is established for this system to function most efficiently, I'll no doubt "Russian Engineer" the distance necessary to heat it.
I am insuring a staight shot out of the roof with no elbows. My unit will be approximately 50 inches above the exhaust, and the exhaust on this unit is right on top. My conscern will be regulating the propper temperature as no creasote will have a chance to collect. I need a way to properly display the burner temperature to the first floor. I may start with the burner and then see what it is at the bottom of the unit. Heck, I might put one on each side of the unit and measure the heat loss. I do not forsee a meaningful loss on my set-up tho.
Most discussion about concern from heat loss at the unit is lowering the draw of convectional pull. Your burner may show new personality, but if you think it hampers anything insulate your pipe with that wrap they sell. The name escapes me like so many other things... They also sell sticks you burn to resolve the creasote issue.
I believe the only restriction is not placing these less than 18" from the flue exhaust of your burner. I suspect the unit you have in question puts out 240cfm. Miracle heat by any chance? I have a 6" flue and they gave me adapters to use the 8" unit. I don't want to restrict the flow any more than necessary. Results will vary upon the application of it.
I'll be happy to report back when this is over, believe me.
Right now I'm stuck looking for an Oval to 6" flue adapter for the burner. I may reach the upper side of 25k btu. They claim 30k but that's probably 18" away. Heat does rise so I would install it real low VS real far away. You get more heat. That's probably the best advice anybody can give you right there. The rest is all variables with stove size flue size blah blah blah and a huge math problem.
What chain would you reccommend for cutting a hole in the floor and a couple joists?
