The ATL-HV series of chilled water air handlers represents an improved design approach to low-profile, draw-through air handlers. These "open top" units allow easier maintenance access and reduced dimensions overall. The top panel of ATL units can be removed for maintenance access to the blower(s). In this way, the unit can be serviced without disturbing the drain pan. The drain stems face aft (toward the blower side) to minimize footprint. Furthermore, the optional electric heaters are mounted on the blower discharge instead of inside the plenum, thereby eliminating the depth added to the plenum area for 6K-18K units.