I'm going to replace my central boiler next summer with another stove looking into the gassifiction types. I have a forced air propane furnace with a heat exchanger in the plenum of the furnace, for the boiler. Are most of these furnaces pressurized units or are they open to atmosphere? The water storage topic, is it the same idea as the 140 gallons of water that my central boiler holds? These storage units, some have copper tubing is there water in the unit itself? I plan on building a wood shed next summer and a building for the furnace, does the furnace shed have to be insulated? I keep hereing they need dry wood, will they burn green wood at all or does it just smolder? I don't know of any one with a gassifing furnace, is there anything unusual to running them or loading them? I'm just wondering if it will be much different then running my central boiler. I'm looking to get a setup that I can fill once or twice a day, and will reduce the amount of wood that I need to burn. Currently in january and febuary when the tempature dips to -30Celcius or -22 fahrenheit I need to fill the furnace 2-3 times a day and usually need to relight it once when I get home from work. How would I size a furnace for my house, It is 2800sq/ft dhw about 25 years old with original windows, well insulated. Last winter I burnt 8-10 cords I'm guessing, of Popular (85%) and ash (15%). Great forum, and lots of info. Thanks for the help.