About 10 years I had a FPX 44 for 3 years and did the job heating a large great room...great big heater and a bit hungry for fuel, air cooled chimney, combustion air was piped in from outside through u-shaped duct in basement to minimize air infiltration. Now for the last 5 year in current house we have a Heat n Glo Northstar...again air cooled chimney, combustion air is straight piped into the unit, additionally there is a chimney cooling kit which adds another pipe from the outside and feeds the base of the chimney air layer from the bottom. Works beautifully as designed to keep chimney cool. So I liked both units very much except for one minor detail...and I am sure you who own them know what it is... When the fireplace is not in use there may as well be a window open in the house as cold air floods down the chimney air cooled sleeve and leaks out all over the place in the cavity the unit is in and then floods into the house. I don't think I am getting too much leakage from the combustion air as the unit looks more sealed than the FPX ever did. So yep you guessed it we are building a new house in 2013...smaller 2,500 sq ft, spray foamed building envelope, trying to achieve a house that is very airtight so that it can be heated with a high efficiency heat pump. (yea yea I know they find nat gas in every hole in Pennsylvania but there are still no pipelines bringing it for residential use...so stuck with oil, propane or electric....electric is cheapest) Still want a wood burner for supplemental heat. Wife is not keen on a woodstove and Masonry Heaters are just too expensive and rather ugly and bulky. So there has got to be a ZC fireplace that meets my needs...with minimal air leakage when not in use... Any help?