Heating, Ventilation, and Air Conditioning (HVAC) plans are used to make and maintain systems of heating and air conditioning. As shown, HVAC plans are an important part of a centrifugal fan, which uses the kinetic energy of the impellers to increase the volume of the air stream, which in turn moves against the resistance caused by ducts, dampers, and other components. As shown in the image, a centrifugal fan is an integral part of an HVAC plan. The speed of the centrifugal fans speeds increases as the air reaches the ends of the blades and is then converted to pressure. These centrifugal fans are able to produce high pressures, which makes them suitable for harsh operating conditions.