The Wolfer Smoke-Cooker differs from some backyard smokers (both comparatively expensive retail ones and those about as expensive to build) in that combustion-air intake is not adjustable. Heat in this unit is reliably maintained within a 40F range by the thermal mass of 12 firebricks, a cast iron boil-off pan to diffuse heat & generate steam (heat transfer is faster in a moist atmosphere), the periodic (average of every 2 hours) addition of partially lit charcoal briquettes, heat conduction through heavy metal pipe & rebar and by not opening the cooker before cook’s expected end time.
Just before the Wolfer Smoke-Cooker is closed, barely lit hardwood chunks are loaded on the front half of the fire grate. That’s enough hardwood to supply a desirable finished product smoke level. The periodic addition of partially lit charcoal briquettes down the fuel/flue pipe keeps hardwood chunks smoldering as-well-as providing primary cooking heat.
Combustion-air enters through 17 holes in the lower-front of the cooker, goes between firebricks, then travels up and across the fire grate. Some of the heat and smoke generated on the fire grate immediately exit the cooker through the fuel/flue pipe, but some heat, smoke and water vapor (from the boil-off pan) rise to the product level then slowly vents out 4 equally spaced holes near the barrel rim. A comparatively high rate of air-exchange helps move potentially harmful smoke solids out of the cooker; thereby lessening their accumulation on end-items. Further, some combustion heat is absorbed then radiated by firebricks and some of it heats the fuel/flue pipe. Heat from the pipe is conducted through connected rebar cooking grates and into meat products.
The cast iron boil-off pan is located directly above the fire grate in order to help diffuse heat throughout the small circular cooking chamber (no corner cold-spots), and to provide humidity which helps facilitate the gelling of tough collagen proteins. The water pan is refilled through a copper tube that can be removed for either the initial positioning of meat or for removing meat from the cooker. Refill water is discharged into the bottom of the pan so the submerged tube will not act as an additional vent. Every couple of hours water is slowly funneled down the brass fitting that is threaded into the smaller barrel bung hole. When the pan overflows fly-ash comes out the fuel/flue pipe; signaling to stop pouring.