For a little introduction.. I've been using this site since I installed my Harman P35i insert last fall in my upper level of my raised ranch. I'm pretty happy with results of that insert. So anyway, this if my first time on this site away from the pellet mill.. In my lower level, the previous owners installed a ND4236 running off natural gas, and direct vented out the rear of the fireplace. That unit - not so happy with. I fired it up today, and was reminded how disappointed I am with the heat output from that. So my question is, what do I need to do to get good heat output in the lower level? I know another p35 could do it, but that set me back about $2800 or so, if I remember right. Which was fine because it is used in my main living corridors. Would I have to spend similar money to get a more efficient and high heat output NG insert? The brochure on the heatilator says 73% steady state efficiency, with 54% AFUE. Seems pretty poor to me. In my rookie searching, I see there are nice units out there by mantis and central fireplace, but those appear to be big money. I'm just like everyone else, trying to get alot of heat for a little cost. Thanks for taking the time to read.