The Counter Flow (CF) coil has an all-aluminum assembly, which helps to reduce the overall coil width and size. Inside the CF coil, refrigerant makes two-passes — once up and then back down — to create a uniformly conditioned airstream. The design allows condensation to drain off the coil during the cooling mode. In the heating mode, the refrigerant flow is reversed, letting the coil work as a condenser coil, rejecting built-up heat into the fresh outside air being circulated to the classroom. According to the manufacturer, the coil’s small footprint frees up room for additional energy-saving options such as an energy recovery wheel and economizer damper. The Airedale ClassMate® DX Cooling and Heat Pump and Airedale SchoolMate® Water/Ground-Source Heat Pump contain the CF coil.