I attached a 12" Whirley bird (Mushroom Vent) to my rocket stove because I had SEVERE BLOWBACK PROBLEMS on an 8" system using a 8-10" and also a 10-12" REDUCER to fit an 8" exhaust pipe and it WORKS GREAT! We live on a hill with tall trees so the blowback caused a lot of smoke to reverse and fill our room with smoke. We considered removing the rocket stove filled with cob, concrete, rocks but the vent is working great and now we have no smoke in our room. I have 20 years experience as a HVAC contractor and came up with the same solutions as you did! Even if the turbine does not turn, it still keeps air from blowing back through the rocket stove system. www.majorsway.org - EARTHBAG HOME BUILDERS - ARK
