We had the air cooled pipe (SL300?) that QF recommends. Moderate climate, ok insulation in the chase. This kept the install costs down. I was looking at the FPX44, and it was considerably more than the 7100, with both using air cooled chimneys. I have the auxiliary air kit installed, which pulls air from the basement up. My hope was to try to draw cold air from the basement, and have warmer air replace it. It doesn't work well (heat does not like to go down). I read here that the warm air duct kits don't work well (factory) except for the RSF system (special kit, big fan, hooks into forced air system). I am thinking about using the AUX air kit to pull air from outside for a system similar to the FPX posi-pressure, and have toyed with the idea of pulling air from the master bedroom with the AUX system, but it is about 40' away. To move air from the master bedroom, I use a small 8" fan on low on the floor, blowing cold air from the bedroom, down the hall to the great room. The warm air rolls back in (you can feel it, and I tried the toilet paper hanging from the hallway ceiling, and you can see the TP move). It warms the room about 6* (long hallway with lots of windows). With the factory heat kit, I thought about getting back into the chase to try to hook up the heat to blow it to the basement, but most of the posts that I found here, indicated it didn't work too well. We did look at the RSF Onyx, but it was a bit out of our price range. I think that is what LLigetfa (member here) has, but I think he has done some modifications to the RSF /furnance connection to make his work better.