The CB-500-CTB large-capacity, used-oil coil tube boiler from Clean Burn can recycle up to 3.6 gallons of used oil per hour. The CB-500-CTB weighs 1,600 lbs. and can heat an area of more than 12,000 sq. ft., with an input reading of 500,000 BTU. The unit has a low-mass design which holds just 20.6 gal. of water, yet 37 gal./min. flow through the coil.