this DIY KIT is very efficient rocket wood stove kit. burns very little wood to heat. I would guess about three 5 gal buckets of elm wood to heat 12 to 16 hours long. prefect for shops and garages. I would guess 100k btu. secondary burn camber, and wood gas mods. some stainless parts. easy clean ash pan. pre order, 7 day eta. if you want a kit yet me know. YOU WELD and PAINT. KIT FORM. $460 cal...