Many different configurations of chambers, fireboxes and smokestacks work well for homemade smokers. Adding height to the stack or increasing the stack diameter can increase the efficiency of the firebox and defeat the smoker's purpose. Smokers require dampers at both the air intake and the smoke outlet to ensure that the fire produces the right type of smoke and to keep the smoke in the smoker chamber. Standard wood-stove flue sections perform well in large homemade meat smokers.
Smokers for curing meat, fish and poultry at home must maintain temperatures between 225 and 300 degrees Fahrenheit for as long as eight hours to safely cook food. Cold smoking partially dried meats requires lower temperatures of about 110 degrees Fahrenheit and can take up to three days, according to the National Center for Home Food Preservation. Installing a smokestack that's too small for the smoker obstructs the draft and keeps temperatures too low for safe smoking. Tall smokestacks can raise temperatures too high and pull smoke out of the smoker too quickly, drying the meat before it smokes thoroughly.
Some manufactured barrel smokers use smokestacks about 3 inches in diameter for smokers with 500 to 580 square inches of grill area in the main smoking chamber. Short vertical risers from 6 inches to 2 feet tall increase the draft and the maximum heat output of the firebox. Reducing stack height on a larger grill keeps smoke in the chamber longer, but other factors also affect the smoking process. Adding green hardwood fuel and decreasing the firebox vent increases smoke and moisture without lowering cooking temperatures because green wood burns hotter than ordinary charcoal, according to the Char-Griller website.
Other functional smoker designs demonstrate that exact smokestack measurements don't determine smoker success. The one-hog smoker designed by Dr. Fred Leak of the University of Florida provides enough smoking space for the largest cuts of a single hog but includes no separate smokestack. Two 55-gallon drums serve as the fire pit and the smokehouse, with the firebox drum buried to the rim in the ground. A buried smokestack between 4 and 6 inches in diameter channels smoke from the side of the firebox to the bottom of the smokehouse barrel. Metal lids placed on each drum serve as dampers for adjusting intake and smoke.
Other homemade smokers work well without discrete smokestacks, including designs recommended by the National Center for Home Food Preservation. To smoke meat, you need a firebox, such as a small hibachi, for heat and smoke; a smoke baffle to spread smoke through the chamber; water evaporating from a pan or from green wood; and a way to hang the meat inside the smoker. Old refrigerators with all combustible materials stripped out make excellent smokers. Cut holes in the bottom sides for ventilating the firebox, then cut slightly larger holes in the top to vent smoke. Metal covers pivoting on sheet metal screws provide damping control.