Just got my furnace installed and have been burning for a day. My first impressions...I am really impressed! So easy even a caveman can do it. It is totally computer controlled and all you have to do is put in good seasoned wood.It controls the draft completely and burn times have been 8 and 8.5hrs. with cherry.Thermostat set to 70. 1840sf ranch No temp. swings mark on 70 in the living room over entire burn and super even heat.Outdoor temp low 20's. Cant wait to see what a load of hickory or white oak will do. The company answered questions when called right away and talked with me as long as it took they knew the stove, electrical connections, plenum, chimney, everything...like the back of their hand, and even called me back when my cell lost call. They tried 5 times! and ended up calling back to my land line house phone. Now that is customer service. This furnace blows no smoke, has ultra insulation( can touch its outside and is just warm). Two layers of firebrick and under that ceramic liner. also stack temps are super low. can touch class a 3 foot above the stove. but box temps are prolly way over 600. The Kumma company is a small family owned place way up in Tower MN. they build these furnaces like tanks. And they are not inexpensive but in this case you really do get what you pay for +... Extra heavy guage steel, high limit alarms, over abundant insulation and zero creosote with good seasoned wood( he told me he has yet to have to clean his chimney after running it 18 years) all these things made it worth every penny to me in peace of mind factor.