We have a 92% eff LP furnace (2000 era) and used to
average 1,300 gallons of LP a year (sampled over 5 years) keeping the house at 68° and the basement unheated. We have an LP furnace, drier and water heater. Drier and water heater consumed about 300 gallons a year at the most. This leaves about 1,000+ gallons a year to heat the house. This 1,000 gallons at 92% efficiency supplied ~ 84,180,000 BTU's over the heating season. Convert those BTU's into lbs of wood assuming 80% wood furnace efficiency (which the Kumma tested out as being), and you are looking at 16,200lbs of firewood needed to produce the same BTU's as a 1,000 gallons of LP in a 92% efficient furnace......
keeping the house at 68° and the basement unheated. Convert to lbs of red oak.....~4.4 cords.
Now we have a Kuuma wood furnace and I weigh all wood I burn and also have a minute timer on my LP furnace in order to keep track of how much the LP furnace runs. I log everything in a spreadsheet, this allows me to compute/track all sorts of things. I burn between 14,600 and 18,250 pounds (4 to 5 cords of red oak) a year while
keeping the house 72°-75° while completely heating the basement AND heating our DHW in winter. I can tell you for a fact, before the wood furnace, we would have used LOTS more than 1,000 gallons of LP if we tried to keep the house at 72° while also trying to heat the basement. Last winter we used 15,115 lbs of wood and 115 gallons of LP (includes what little the LP furnace ran, DHW and drier).
According to my numbers, my wood furnace is making better use of the wood then my LP furnace was making of the LP.
I have a buddy who installed a Daka (Menard's special) the same time I installed my Kuuma. No thank you.....goes through wood like crazy, burns dirty and requires one to constantly monitor their chimney. Because the Kuuma is computer controlled, it's ALWAYS burning optimally, is pretty much smokeless and doesn't require yearly chimney sweeps because it burns the majority of the gasses instead of sending them up the chimney to condense and form creosote. Like with almost everything these days, you get what you pay for. Everything these days is getting cheaper and cheaper. It's hard to find anything quality anymore. When I find it, I don't mind paying for it.
More about the company...a company of SIX employees.
http://www.timberjay.com/stories/poised-for-growth,13580
http://www.duluthnewstribune.com/news/4329352-iron-range-wood-furnace-factory-needs-room-grow