Some History about the Author
David Tjosvold owned his first furnace distributing business in 1965, followed by 2 furnace-distributing businesses over the next 6 years. In 1973, soon after the Arab oil embargo, a manufacturing business to be named Yukon was added. Yukon began developing warm air furnaces to burn wood and coal. In 1976, it was decided to develop a warm air wood furnace that would also be able to burn Natural gas, LP gas and oil in the same furnace with the oil or gas burner being able to ignite the wood. By 1977, Yukon introduced the first UL Listed wood/coal warm air furnace, followed by the first UL Listed wood/oil, then wood/gas and then wood/electric. I was then chosen to be on the first UL Industry Advisory Board for wood burning appliances. We then developed the first UL Listed oil condensing furnace, followed by the first UL Listed gas condensing furnace. Condensing furnaces are about 90%+ efficient and require only a PVC vent instead of a traditional chimney. Still later, an outdoor wood boiler was manufactured. I am giving you some of my background so that what you read here comes from my 32 years in the industry.