Forward Curved.  Forward curved type wheel used primarily in low pressure heating, ventilating and air-conditioning applications such as domestic furnaces, central station units and packaged air-conditioning units. Lower efficiency than airfoil and backwardly inclined wheels but with similar housing designs. For a given duty, the wheel is the smallest of all centrifugal fan types and operates at the lowest speed. Pressure curve is less steep than that of backwardly-curved bladed fans. There is a dip in the pressure curve left of the peak pressure. The horsepower curve rises continually toward wide open delivery and this must be taken into account when the motor is chosen. Single width units vary in size from 122 to 720 with performance capabilities from 1000-428,000 CFM and static pressure to 18". Double width units vary in size from 122-330 with performance capabilities from 1200-700,000 CFM and static pressure to 10". Temperatures to .500 Fahrenheit.