You said you had a second vent where is that vent located? Is it on the oposite end of the house from the stove? I would see which vent the air natually travels to and use that one for return piped directly into your air intake on the convection fan. Use one of the fans to push the air to the intake and use the other to help pull the heat off the stove. If your two vent are far enough apart you should be able to get some convection going. Until then you stair case is practicaly useless just like mine was. The air just mixes in the stair case it doesn't have a good flow. Keep after it I know how frustrating it can be but after some playing with it I have my house toasty all over.