I've been using an outdoor Bryan wood furnace for the past 15 years. I have 40 acres of heavy forest, so there is no shortage of dead/damaged trees throughout the year. I chainsaw/split about 8 or 9 cords every year, and take both dead and damaged live trees. I burn mostly the dried out(seasoned) wood, but in the, evening before bedtime, I toss in 3 or 4 pieces is fairly green wood. That keeps the fire going during the night, and then, the next morning I still have a bed of good coals to quickly bring the fire back to life. The "green" wood does build up a small amount of creosote in the furnace/chimney, so every couple of weeks I run the furnace for a couple of hours with the ash door open a bit, and that creates a very hot fire, which quickly burns off any excess creosote. We have a total electric house, and I figure I save between $1000 and $1500 a year on the electric bill, this way....plus, I get all the good physical exercise of wrestling thousands of pounds of wood every year. I've probably got about $6,000 invested in the furnace, log splitter, and 2 Stihl chainsaws...but, I've saved 3 or 4 times that amount on the electric bill, over the years.