Vertically integrated dual return assembly

A mixing chamber assembly to foster air stream collisions to promote mixing, the mixing chamber assembly comprising:

• a mixing chamber outlet at one end;
• and
• a hot duct discharge at an opposite end, opposite the one end, the hot duct discharge positioned relative to a flat surface so that burner output from a burner in fluid communication with the hot duct discharge leaves the hot duct discharge and the burner output flowing adjacent to the flat surface;
• and
• a kiln return air supply positioned to deliver kiln return air substantially perpendicular to the burner output flowing adjacent to the flat surface so that the kiln return air collides with the burner output which is constrained by the flat surface which is adjacent to the burner output, the kiln return air colliding to promote mixing of the kiln return air and the burner output.

A system for circulating heated air to treat lumber, the system comprising:

• a structure having a floor, a roof above the floor, a first end and a second end with at least the first end having an opening so that lumber may be moved into and out of the structure so that stacks of spaced lumber may be treated, a wall along a first side extending from the first end to the second end, and a wall along a second side opposite from the first side
• a direct fired burner which provides heat to an air blending chamber which provides heated air to the structure though use of a supply duct and a blower;
• a set of at least one circulating fan located on in a center wall located above a horizontal fan deck and below the roof;
• set of dampers and a pair of return ducts to allow for kiln return air to be drawn
• from the first side of the structure relative to the center wall when the at least one circulating fan is causing a pressure gradient to force air through the stacks of spaced lumber from the second side to the first side;
• and
• from the second side of the structure relative to the center wall when the at least one circulating fan is causing a pressure gradient to force air through the stacks of spaced lumber from the first side to the second side;
• both return duct feeding kiln return into a first section of a vertically integrated dual return assembly and flowing in a first direction before crossing over into a second section of the vertically integrated dual return assembly and proceeding in a second direction, opposite of the first direction, the kiln return air entering into a dispersion chamber with a delay table that receives a flow of burner output gas from a burner hot duct discharge oriented perpendicular to the flow of the kiln return air entering into the dispersion chamber, and
• the kiln return air and burner output gas at least partially mixing before entering an air balancing chamber and traversing the air balancing chamber to enter a suction side of a blower and returning to the structure through a supply duct.