I am looking to put a free standing direct vent gas stove on the hearth and vent it up my existing chimney. This will require a rear vent I think. My issue is what size stove to get for my space, which is an open floor plan with a loft above. The main living/dining "great room" I'd like to heat is 15 ft x 31 ft in size. This space has a slanted ceiling that follows the roof line -- it is 8 ft along one long side of the room but about 15 ft along the other long side. Furthermore, along most of the long side with the 15 foot ceiling, there is a loft area on the second floor (above bedrooms on the first floor that are closed off from the great room). So heat from the great room will go up and then "spill over" into the additional space of the second floor loft. The loft room is 19 ft x 10 ft, with a tall bank of windows along one long side and a very short "garrett" wall of just 2.3 ft along the other. What size (BTU output) should I plan to put in the great room, with this configuration of space? The house currently is heated with 1970's electric baseboard heat, and I am looking to augment that or effectively replace it at least in the living/dining space with the gas stove (on a thermostat). One guy I spoke with said I don't need to count the loft area, as it will get heated "for free" by the heat rising, after it has already heated the downstairs area. But he suggested I do have to account for the higher ceiling along the one wall (the cathedral ceiling). I'm also concerned that with this configuration, the loft area will get too hot while the downstairs will remain chilly. I do have a ceiling fan in the loft area and also a return vent arrangement to help redistribute the heat, but might I need something more? I have a Jotul gas stove at my old house, mostly for ambience as there was no fireplace, and I just love it -- instant coziness with clean and quiet heat. So I'd really like to put one in my new place, and the hearth is a natural spot for it, I don't plan to every lug wood and burn a wood fire in the fireplace. But the space to be heated is so unusual that I don't know how well it will work or what size stove I should plan for. Help!