Clair Wilson and his sons operate a farming and fabrication business near Winchester, Ill. They have a huge 120-ft. sq. shop. To heat it they built a giant wood-burning furnace into an embankment next to the shop. 

"We use a skid steer with a grapple to load up to three logs at a time. The logs measure 14 to 16 in. in diameter and are up to 6 ft. long," says Clair. "A pair of big hydraulic cylinders are used to open the lid. The cylinders are powered by a hydraulic pump inside the shop."

Located just outside the shop walls, the furnace was built from 1/4-in. thick steel plate and measures 7 ft. sq. There's a full-wide door at one end of the stove that can be opened to remove ashes with the skid steer. The furnace's hinged lid contains a water jacket that will eventually be connected to pipes embedded in the shop floor. The plan is to circulate heated water just beneath the floor.

For now, the shop is heated with hot air that's pumped through a plenum and into the shop by two large furnace fans. The plenum runs up one wall to the ceiling and across to the other side of the shop. 

A blower mounted outside the furnace pushes fresh air into the firebox to feed the fire.

The shop's in-floor heating system goes back a ways. "We installed a home-built radiant floor heating system in the shop in 1994 and used a commercial liquid propane boiler to heat the water," says Clair. "We placed a series of 1-in. schedule 80 pipes 1 ft. apart under the shop floor. We built the wood-burning furnace because of rising propane prices."

He says they load logs into the furnace about once a day. A 30-ft. length of 10-in. dia. irrigation pipe serves as a flue for the furnace.