An inlet duct system includes a duct body having a bottom wall and two side walls having at least one opening. An adjustable internal baffle is secured to the duct body such that the internal baffle can be positioned in multiple locations within an internal cavity defined by the duct body, inhibiting the flow of air between a front portion and a rear portion of the internal cavity. A first side duct is removably attached to the duct body and forms an air flow chamber that receives a fluid from an opening in one of the side walls and delivers the fluid above the duct body. A first side baffle is positioned within the air flow chamber, adjacent the internal baffle, inhibiting the flow of air between a front portion and a rear portion of the air flow chamber.