Monster Wood Furnace Burns A Dump Truck Load At A Time

2005 - Volume #29, Issue #3, Page #44

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Steve Kruel doesn't bother splitting firewood for his monster furnace. Instead, he fills it with his skid steer, adding a dump truck load of 4 to 5-ft. long chunks every three to four days.
"We got tired of paying for LP gas," says Kruel. "Now I pull logs and branches out of the woods, cut them to length, and load my dump truck with a skidsteer. Last year I used 48 dump truck loads to heat a 12,000-sq. ft. greenhouse, my house and an apartment building."
To handle wood in such large amounts and heat so much space, Kruel needed an industrial-sized furnace. Unable to locate one large enough, he built his own. The firebox is big enough to drive right into at 8 ft. wide, 14 ft. long and 10 ft. high. The water jacket, insulation, and exterior dimensions are 14 ft. wide by 24 ft. long and 14 ft. high. A ramp allows Kruel to load the firebox from the top with his skid steer.
"There is no shortage of free wood between cleaning up after loggers and people from Chicago who buy some land and want it cleaned up," explains Kruel. "I also have a guy down the road with a sawmill who will give me all the slabs I want."
The big furnace wasn't cheap as Kruel used all new steel. He figures today's cost would probably be twice the $12,000 to $14,000 he spent two years ago.
Kruel designed the exhaust system to get the most out of the wood he burns. The flue exits the firebox at the rear, running forward through the water jacket nearly to the front of the furnace and then doubling back to the rear before exiting through the exhaust stacks. The 18,000-gal. water jacket itself is insulated with foam. The hot water pipes were wrapped with a bubble wrap-type insulation before being inserted in drain tile and buried in the ground.
"The longest run is 300 ft. to the house, and it is plenty hot when it hits the heat exchanger," says Kruel. "I don't know what temperature it gets to in the firebox, but I figure it would melt if it wasn't for the water jacket."
Snaking the flue back and forth means the smoke cools considerably before exiting. That can result in a carbon buildup in the flues, something that might cause a dangerous chimney fire in other furnaces. With the monster furnace, that is a positive.
"I did have it plug up on me once when I was burning slabs of soft wood," recalls Kruel. "Cleaning it out was easy, I just opened it up at the rear, put in a torch and set the plug on fire. It burned right out."
Contact: FARM SHOW Followup, Steve Kruel, Hillside Greenhouse and Land Shaping, 15111 Hwy. 61 S., Boscobel, Wis. 53805 (ph 608 375-4202; email: hillside.greenhouse @outbound3.mail.tds.net).

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Monster Wood Furnace Burns A Dump Truck Load At A Time ENERGY Wood Burners (65) 29-3-44 Steve Kruel doesn't bother splitting firewood for his monster furnace. Instead, he fills it with his skid steer, adding a dump truck load of 4 to 5-ft. long chunks every three to four days. "We got tired of paying for LP gas," says Kruel. "Now I pull logs and branches out of the woods, cut them to length, and load my dump truck with a skidsteer. Last year I used 48 dump truck loads to heat a 12,000-sq. ft. greenhouse, my house and an apartment building." To handle wood in such large amounts and heat so much space, Kruel needed an industrial-sized furnace. Unable to locate one large enough, he built his own. The firebox is big enough to drive right into at 8 ft. wide, 14 ft. long and 10 ft. high. The water jacket, insulation, and exterior dimensions are 14 ft. wide by 24 ft. long and 14 ft. high. A ramp allows Kruel to load the firebox from the top with his skid steer. "There is no shortage of free wood between cleaning up after loggers and people from Chicago who buy some land and want it cleaned up," explains Kruel. "I also have a guy down the road with a sawmill who will give me all the slabs I want." The big furnace wasn't cheap as Kruel used all new steel. He figures today's cost would probably be twice the $12,000 to $14,000 he spent two years ago. Kruel designed the exhaust system to get the most out of the wood he burns. The flue exits the firebox at the rear, running forward through the water jacket nearly to the front of the furnace and then doubling back to the rear before exiting through the exhaust stacks. The 18,000-gal. water jacket itself is insulated with foam. The hot water pipes were wrapped with a bubble wrap-type insulation before being inserted in drain tile and buried in the ground. "The longest run is 300 ft. to the house, and it is plenty hot when it hits the heat exchanger," says Kruel. "I don't know what temperature it gets to in the firebox, but I figure it would melt if it wasn't for the water jacket." Snaking the flue back and forth means the smoke cools considerably before exiting. That can result in a carbon buildup in the flues, something that might cause a dangerous chimney fire in other furnaces. With the monster furnace, that is a positive. "I did have it plug up on me once when I was burning slabs of soft wood," recalls Kruel. "Cleaning it out was easy, I just opened it up at the rear, put in a torch and set the plug on fire. It burned right out." Contact: FARM SHOW Followup, Steve Kruel, Hillside Greenhouse and Land Shaping, 15111 Hwy. 61 S., Boscobel, Wis. 53805 (ph 608 375-4202; email: hillside.greenhouse @outbound3.mail.tds.net).

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