When Robert Kerr decided to heat his 30 by 32-ft. farm shop, he knew he couldn't justify spending a lot of money but he also knew he'd need a good-size stove or furnace to do the job. In addition, he wanted a stove that would run automatically without much tending on his part.
He decided the only solution was to build something himself. "I built this 115,000 btu oil furnace that puts out a tremendous amount of heat yet burns just 2 1/2 to 3 gal. of fuel in a 12-hour period. Operation is totally automatic with thermostatic control," says Kerr, noting that he's had almost no problems with the furnace in 5 years of use.
It consists of two 45-gal. barrels mounted one on top of the other. The barrels are surrounded by a sheet metal housing that captures heat thrown off by the barrels. A squirrel cage fan, off an old furnace, blows air into the housing around the barrels. Hot air comes out an outlet at the top of the housing and blows into the room.
A 1-gal. per hour oil burner mounts on a small stand outside the end of the bottom barrel. It points into the end of the barrel, shooting directly against a 1/ 4-in. thick steel baffle plate mounted about 2/3's of the way down the length of the barrel. Heat passes around the top, sides, and bottom of the baffle plate and up through a section of stove pipe that runs from theendof the bottom barrel up to the end of the top barrel. A stove pipe exits out the top of the top barrel.
Kerr says the top barrel acts like a heat exchanger that keeps excess heat from exiting up the chimney. Air blown in and around the barrels by the squirrel cage fan draws off heat from the barrels. A fan control sensor mounts in the top barrel, turning the squirrel cage fan on or off as needed depending on the level of heat in the barrels. An "old-style" burner control unit mounts in the pipe between the two barrels, turning the burner on or off as temperature in pipe rises or falls.
"The amount of heat you can get out of the stove depends on the size of the burner nozzle you use. I'm using a 115,000 btu nozzle. One improvement I plan to make is to run ductwork from the fan up to the ceiling area so it will draw warm air down from the ceiling which should help circulate air even better than it does now," says Kerr.