It pays to make sure that a ventilation system performs properly and efficiently. Select a fan that meets your needs for reliable performance at a reasonable cost over the life of the product. Fans use the most energy of any component of the ventilation system. The more aerodynamic the fan, the more air it will move per kilowatt of electricity. Match the blade size to the motor size. A fan blade that is too large or too small for the motor will cause it to run hot and will not last as long. Add a cone to the exhaust side of the shroud to spread out airflow. This is more efficient than abruptly slamming the air into a wall of still air outside. Check beltwear four times per year. A worn belt rides lower in the sheaves reducing airflow significantly. Dirty shutters can reduce airflow by 20%. Maintain motors, inlets and bearings by cleaning and yearly lubrication.