As many of you now I installed a Kuuma vapor fire last year. Well I just got around to cleaning my chimney for the last piece of info needed to give an accurate opinion. The chimney was as clean as a whistle, A little dust ash, that's it. There was a little soot in the inside Single wall pipe, 1/16 of an inch. This furnace was everything they said it was. This was my only source of heat last winter, if it didn't work I was screwed. It worked flawlessly. My house about 2,000 sq ft, NEVER dropped below 70* Even on the coldest days where some peoples boilers could not keep up. This furnace is said to equal 100,000 btu fossil fuel furnace. Well a coworker that lives 5 miles away with a 125,000 BTU oil boiler on the coldest days could not keep his house out of the 50's. First time that has happened to him in the 20 yr's he's been there. My house was 72*. This wood furnace is as easier to use than any wood burning appliance that I have seen. Almost as easy as fossil fuel, the exception of course is that you have to put wood in it twice a day. Even that is easy, scrape the ash down the grate, pull the coals forward, toss in your wood, close the door and walk away. Even my wife can use it. (and that is saying something. she is VERY girly) Don't come back for 8 to 12 hours. 1 piece of wood = 1 hr of burn. I never loaded the furnace full, so I don't know how long a burn it can have. But it can do at least a 12 hr burn 3/4 loaded. I got the h2o coil with it, which gave me 3 free showers a day. Wood usage was the same amount of the same wood as the winter before with the wood stove. If you recall that winter 2 yrs ago was no winter at all. Last winter just wouldn't end, needed heat in june for crying out loud. So twice the winter and hot water with the same amount of wood, and 1 million percent easier. As for customer service, they are amazing. I have never encountered such good service. There was trucking damage upon delivery, They wrote me up a repair quote the same day. I had an issue upon start up on a Saturday morning. I called them and the owner answered the phone and had my issue resolved in minute's. ( a spring adjustment) I called on a weeknight at 7 o'clock with a question, again the owner answered the phone and answered my question. Darrell ( the owner) is truly excited by his unit, and how it works. American made, with true American quality, with old time American customer service. I am very pleased with the Vapor fire 100 and would happily recommend one to anyone. The only thing I don't like is it's hard to remember the spelling of Kuuma. P.s It works great when the power goes out as well. And flue temp is around 250*. P.ss I loved showing the guy's that ride along with me all the houses that have smoke coming out of there chimney's, then driving by my house and seeing nothing coming out of mine, not even the heat squiggles. They could not believe I had a fire going at the time.