movement being allowed around the axis of the bolt 108 this movement in the coupling allows adjustment of any space between the coupling 42 and the facing opening in the dryer housing 12 thereby facilitating final adjustments during mounting of the combustion chamber 24 in the dryer system 10 the operation of the combustion chamber 24 will now be discussed briefly with particular reference to fig3 and 4 the blower 44 fig2 is started to circulate air through the housing 12 fig1 with heated air being drawn into the housing 12 from the combustion chamber 24 as a result of exhaust air being pulled out of the housing 12 by the blower 44 the burner assembly 50 produces a flame that extends through the heating cylinder 74 toward the front end 62 of the combustion chamber 24 with the flame produced by the combustion chamber of the present invention extending substantially the full length of the chamber approximately six feet for the embodiment described for better mixing with the air being supplied to the dryer fresh air enters the heating cylinder 74 in the area between the heating cylinder 74 and the burner cylinder 72 and is heated by the flame as it passes through the heating 74 at the start of the cycle both the slide gate 80 and the exhaust gate 86 are closed hot air is supplied through the aperture 42 in the first side wall 64 to the dryer housing 12 as the exhaust air heats up the exhaust gate 86 may be opened to recycle a portion of the exhaust air when the cycle is about 25 through the.